Rek'Sai Build Guide by SadisticShinigami
Not Updated For Current Season
Full build exemple
You are fed as hell and want to destroy the enemy
Not Updated For Current Season
Threats to Rek'Sai with this build
|Amumu||EASY match-up. Poor Amumu is really slow to clear his camp early game and consume a lot of mana, if you counter jungle him he just CANNOT DO ANYTHING to fight back and has to run away, if he doesn't he is dead. Steale his blue buff and his camps, you will quickly make him useless and struggling hard. Still do not underestimate his potential in teamfight, but if you destroy his early game he will probably be underleveled and squishy.|
Hi everyone ! I'm a platinium player maining jungle on EUW Server. I started to play League of legends at the end of Season 3 and reached platinium in beggining of Season 5 playing mostly Rek'Sai (Nocturne and Skarner when I could not). I have a lot of normal games with this champion and tried a lot of different builds and tactics. My goal was to write a guide explaining how to play her once I reached Platinium. Now that this is done I feel like being in good position to share my knowledge about this champ and the jungle in general. If you disagree with my build/comments/tips etc... or got any specific questions about how to play this champ, I will be delighted to take your comments into accounts and will not hesitate to update my guide if I missed some points.
Keep in mind that I got out of Gold and reached Platinium playing Rek'Sai, what I am trying to do with this guide is to explain how I mannaged to do that. My way to jungle and play Rek'Sai might not be the best of the world but playing this way was at least enough to reach Plat, so if you're stuck in bronze/silver/gold, this should help you to rise your Elo :)
Here is my youtube channel, lot of league of legend vid featuring Rek'Sai are coming up soon !
Different type of junglers
As you already know it, even if each champion is unique, there are still several class of junglers, I think it's apprioriate to start this guide by defining each one in order to understand match-ups as well as the way Rek'Sai should be played.
- The Sumo
The Sumo is a CC heavy Tank, their damage tends to be weaker than other junglers, however what he lacks in burst, he makes up for in HEAVY CC and unmatched tankiness. They will tend to get few kills and lot of assists most of the time, their job is to initiate teamfight, protect their carry and silence/stun/block/grab enemy carries. Their mission is to force the focus on themselves during teamfight and prevent marksmen or casters to fight back. Champions of this category include; Zac, Nautilus, Sejuani, Gragas, Malphite, Amumu and many others.
Major weakness : most of them tend to be slow farmers, they are very vulnerable to counter-jungling as they perform poorly in 1 v 1. Do not hesitate to steale their camps, if they can't get gold they can't buy items, therefore they can't build tanky, if they get late in their build their utility in teamfight will clearly decreased.
Careful : they are often underestimate, do not make this mistake. First their damages are not so low as we could think, most of the time they just work more over-time as opposed to champions having instant burst (their huge amount of HP and Armor/Magic Resistance give them the time and survavibility they need to spam their damages over the fight, they might not look impressive at first, but will still influence the teamfight so keep your eyes open when they get close to your carries.) Also even if they must never be totally ignored, never focus them over squishy champions, because this is exactly what they want you to do.
Let's underline this : early game is the best moment to kill them as they will have not yet a tanky build and definitely not enough damages to fight back as their skills are more CC focused.
Your mission as a sumo : gank a lot early game, build tanky the fastest possible, in mide/late game, be always the front-line for your team, initiate the fight, try to put your CC on enemy carries in order to disable them and allow your team-mates to kill them. Bring chaos among the enemy team and PROTECT your own carries as much as you try to prevent the enemy ones to do their job (cancel their channel with your cc for instance).
The Ninja, as his name implies, is very mobile champion excelling in quick assassination. This guy is a real ghost, you never know where he is, if you spot him you must catch him quick, otherwise he will vanish in a puff of smoke. This champion got instant burst that he will use to delete your carries if there is any door left open for them. DO NOT let them the possibility to get behind your lines or this might be already too late. We can regroup in this category Shaco, Kha'Zix, Rengar, Evelynn and Elise for instance.
Weakness : those guys are very squishy, since the rework of the jungle they tend to struggle early game against the creep while farming, you can turn it into your advantage and try to kill them while they are clearing their camp, but if you do so you must be fast, they might be quick to die once caught, but their kit usually include a lof of spells to escape or dodge your abilities, also they master into braining their opponents using stealth moves, usually a pink ward should help you to break their mecanics. Keep this in mind : they will often not show themselves at first when a teamfight is starting, however they are most of the time close-by and are just waiting for the good moment to go in and murder your carries, tell your team to stick together and keep an eye on those who get a bit farer from the rest of the crew.
How to fight them : counter-jungle them, if they get late in their build they will get not enough damage, if they get underleveled and cannot build as much damages as they should, they will not be able to fulfill their mission.
Careful : They will often ward your jungle, if you get low on a camp and have no vision on them at the moment, you can start to be paranoid, try to ward your jungle with pink and unward it the most you can coze they just master in the art of killing those in dangerous situation, do not give them the opportunity to do what they are the best at.
Special note : Rek'Sai is clearly a great pick against assassin's, her vision while burrowed will be a nightmare for them coze you will be able to predict if they are nearby and in which direction they are planning to get away, so always remember to activate your W when a Rengar or a Shaco enters in stealth mode, this will drive them crazy.
Your mission as a ninja : Never initiate a fight, always wait for your team-mates to engage, analyze enemies abilities cd, choose the most vulnerable target, go in, kill her, then disengage, when there is no opening, try to splitpush in the mean-time, but keep an eye on the map and tell your team to not fight while you're far.
Lying in the middle between an assassin and a tank, this one is a very versatile jungler. They excel in the ability to gank. They will generally assume the role of an assassin early game and later switch to a more tanky one. Their kit is pretty balanced, they got lot of gap-closer abilities or dashes, are generally monotarget with a bit of AOE and a very noticable burst power. Their build will often be a mix between damages and survivability as their strenght dwells in their ability to adapt to different situations as long as the game evolve. In this category we can regroup the most popular junglers, such as Lee Sin, Vi, Xin Zhao, Wukong or Jarvan IV. They are the most balanced class of junglers.
How to fight them : those guys will spend most of their time trying to gank instead of farming. This allow you to steale their camp and their buff as they will tend to clear them a bit in late. Their abilities might not be as much cc oriented as tanks, but they still got very strong crow control when used on a squishy target. Late game you cannot totally focus them, as they will build enough tankinness to be able to survive a few punch, but you can't also ignore their damages. Try to protect your carries as much as you can against them without forcing too much your focus on them. The best way to deal with them is generally to get rid of them before the teamfight or try to bait their most annoying ability on yourself instead of your carries, once they are in cd they usually dont have much to fight back.
Weakness : ganking being their favorite hobby, they tend (a bit) to neglect objectives, such as split-pushing and drakes, also most of them (except Vi or Wu-kong) will fall-off late game, the most of their job will hence be early game. Unline assassin's they are often very predictible, easy to brain and dodge their ability. If they fail their dash they become poor chasers, with Rek'Sai you should not have trouble getting in their jungle and take what you need before they even notice it. It's often easy to know where they are, what they are doing and what they try to do, so you should have no problem in predicting where they are heading, try to use this advantage to counter-gank them effectively and/or take objectives while they are busy somewhere.
Your mission as a ranger : Gank as must as you can early game, when there is no possibility to gank try to kill the enemy jungler while he is farming, keep an aggressive gameplay all the time. When comes mid/late game, you can initiate fight, or jump in right in second and do your best to zone out enemy carries. You are the bully of the team.
Here is my favorite type of jungler ! Stalkers, as their name suggest, are just the most made for jungling ! There is no faster farmers than them, they will clear their camp excessively fast and are just MASTERS IN COUNTER-JUNGLING. All their kit is focused on doing objectives the fastest way possible. They've got the highest mobility from all other type of champions, are generally a mix of tankiness and damages just like Rangers but with a lot more AOE abilities. They got few CC, but god the few they have are terribly annoying, usually able to be spammed and will often result in a kill or a flash when landed. Another thing they are definitely the best at : CHASING. You whish to escape them? They will hunt you down ! Nobody run faster than them, also they got the greatest map control compared to any other junglers. Late game they will usually be a nightmare in split-pushing if you don't keep an eye on your towers. If you let them an open lane, they will devour waves of minions one after another before you find them already smatching your towers/inhibs with fury. The all map is their territory, they can roam around here and there and feel safe to do so because they know that they can easily escape if the enemy team try to catch them. What about ganks? They are generally not the most aggressive junglers early game (except one ^^), so that enemy team tend to feel safe and ignore them, but be warned : once they caught you it will be very difficult to escape them. In this category we can list Rek'Sai, Udyr, Skarner, Nocturne Shyvana, Hecarim and Warwick
How to fight them : well, lot of them rely a lot on farming, if you steale their camp and make them fall behind, however do not loose too much time doing so, because they will anyway, if you're not another stalker yourself, very quick come back if you let them breath, so I will more advice you this tactic : focus hard on ganking your team-mates, if you really put their team behind early game, this will be lot more difficult for them to get control of the map. Try to get a drake each time you lead a successful gank botlane or while they are busy somewhere, because remember that : it will be lot easier for them to clear drakes than you do, so do not miss any opportunity. The most towers you get in the game, the hardest it will be for them to get control over drakes, also never let them the opportunity to free push one of your lane, coze this might result in the loss of a tower... Or more...
However, do not send all your team to chase them down, they will escape you most of the time and play with your nerves while dodging your CC, this can be a bait allowing their team to take important objectives while you are loosing time attempting to kill them.
Useful tip : ALL OF THEM are heavy auto-attackers, Thornmail will force them to respect you.
Weakness : most of them depend on their build and farm to get useful for their team, also lot tend to be very mana hungry as their clear speed and split-pushing potential generally require to spam abilities in order to get through objectives, stealing their blue buff will usually really upset them. Also : all of them are auto-attackers with high mobility, which means red buff considerably boost their gameplay, if you can get their it will weaken their ganks, do not neglect that. Almost all of them tend to afk farming a bit early game (some a lot), so maximize pressure early the most you can, as long as the game goes, it will be harder and harder to deal with them.
Why, being a jungler main, and a stalker lover, do I prefere Rek'Sai over the rest? The answer is simple : Rek'Sai is a stalker which main strenght lies in the fact that she is a Stalker without the main weakness of this particular class of junglers !!!
Let me explain : Udyr or Shyv are known for their weak ganks early game, Udyr needs items and mobility to successfully get close to his targets as he has no dash or ranged cc, Shyvana got zero CC and needs to farm and counter jungle a lot early game as she will neglect a bit lanes. Warwick ganks are weak pre-6, Skarner, just like Udyr, needs a lot of mana and relies also a lot on his items to be able to unleach his full potential, What about Rek'Sai? She knows none of that ! Her main advantage compared to other stalkers is that she doesn't need mana but unlike Shyvana got a dash at level 3 and a CC. She might have ONLY ONE CC but the one she got is just extremely powerful in ganks and mana free ! + another main advantage : Rek'Sai doesn't depends on her build and items just like an Udyr or a Skarner will, in fact she is pretty independant all by yourself, that's why I only get a brutalizer (merged with the jungle item) and focus later only on tankiness and survavibility. She doesn't need to get devourer stacks in order to deal damages, she doesn't need to spam an ability at the coast of mana to farm or a lead a successful gank.
So, all that being said, people might wonder, why enlisting her in this class and not in another? Well, despite all of the weakness she lacks, she is definitely a stalker. Her gameplay is clearly splitpushing oriented, her farming speed is just insane and her Tremor Sens allows her to hunt down her preys like no one (even in stealth) + her ult allows her to quickly come back into the map in order to keep the pressure op over lanes or to take objectives.
For all this reasons, being originally an Udyr/Skarner fan, I quickly fell in love with Rek'Sai who remains a safer pick in general (however let's state this, her late game is definitely under those two ones, but as opposed to them she will be able to start the pressure very early in the game which make her so interesting).
Your mission as a Stalker : Always do your best to overfarm the enemy jungler, keep a strong map control, go get objectives each time you get an opportunity, mid/late game you will have to splitpush and be right back in the battle in order to tank for your team while still dealing lot of damages. You must keep the pressure up the most you can.
Jungle Road and more
Always remember one thing : there is not one road in the jungle but many. Often when I play jungle some players enjoy to criticze stuffs like "why not starting golems" etc.. etc..., this tend to tire me. DO NOT listen to other people comments, this is your role, as a main jungler you know for sure better than them what you are doing and why, do not loose time if some toxic player wants to force you to invade or to start a camp when you don't want, just do the way that fits the best to you and the champ you picked.
HERE IS MY WAY to start the jungle with Rek'Sai :
First I like to start bot side, why? Because you will get more help on your camp, so it means clearing it faster, also you don't want your toplaner to be late in his lane and become first blood because of one level missing (this is not season 3 anymore :D).
Start botside, if blue is at botside, then smite Graup (I used to smite blue buff when it was giving back health but I don't do it anymore as now smiting him only provide you mana, which you don't need at all).
Smite graup, if the support is a tank playing targon, like Leona or Braum, ask him to tank Graup for you, he will get full hp when coming back in lane very quick without using any pot. This is very helpfull and might save you a potion. If the support is squishy, just forget it, go ahead and tank it.
Smite Graup just after it spawns, so you reset the CD of smite faster and can enjoy the buff earlier. Then quickly go to your blue buff and clear it (if there is a SHACO jungle, FORGET GRAUP and start your blue buff right away coze if not he might kill you when you are doing it which you OBVIOUSLY doesn't want to happen).
After that, if you are a bit low, got get the crab in the riven between botlane and midlane, this will give you time to gain HP back, provide you nice amount of gold, and maybe prevent an early gank botlane to succeed. BUT IF YOU DO THAT BE CAREFUL, if you are not lucky, the other jungler might get around while you are doing it, so keep your eyes open, this is still a bit risky and you might die over that. If the enemy jungler appear, do not greed on the crab and just go away (of course once again, if enemy jungler is a shaco, forget the crab for now).
After your blue buff or the crab (if you decided to do it), just RUSH YOUR RED BUFF), the smite cd should have reset, start it, when it starts to get low, just smite it and you will get HP back (ALWAYS CHECK THE BUSH before starting your redbuff, the enemy jungler might camp in it, drop a trinket there if you want to take no risk).
Once this is done, you can do golems if you have enough hp, if it's a bit tight, don't forget you can engage with missile, bump, then reset your bump once it's possible to finish off your golem (when a camp is a bit hard to get I burrow myself, get a bit farer (so I get hpback), launch a q spell, bump it again and keep auto-attacking it, in most of situation this can help you to finish off a camp when your hp is a bit too low.) If you can't do the all camp, you can just do the little golem, this will still be more gold to spend in the shop after your first recall. After that, get back to base (except IF there is a very good opportunity of early gank, enemy toplaner is already low and you can do something, then try to gank him if you have enough HP left)
OK STEP ONE IS COMPLETE, now you are in the shop, what to do next? EVOLVE your machete into Stalker's Blade, this is A MUST HAVE ITEM ON REK'SAI (and most of junglers in my opinion) as it will provide you a little free CC that will really help your ganks, do not underestimate it. What do buy next? BOOTS, YOU NEED BOOTS because MOBILITY in the jungle is EVERYTHING. If you move faster than enemy laners, your gank has more chance to succeed, as a jungler mobility is even more important than damage because with Rek'Sai sometime JUST ONE SINGLE BUMP can result in someone death if your laner follow your gank the way he should. Some junglers prefere to complete their jungle item before getting boots, this is their choice but I prefere to rely on speed when I'm ganking.
So youv'e got your Stalker's Blade, your boots, something more to buy? Yes, a pot or two, early game the jungle is still dealing heavy damages, having a pot will help you to gank a lane being full hp (DO NOT GANK a lane when you have no health (except in very specific situation but remember it's always risky). If you give a kill to the enemy laner, you will probably make your team-mate loose his lane and getting snowballed, THIS IS NOT what you want to happen, YOU WANT your team-mate to snowball his lane, so be careful to not destroy his lane.
When I play Rek'Sai, I try to let the kill to my laner, generally, but sometime picking up the kill will still be worth on you. You are not Maokai, you are not Nautilus, you are Rek'Sai and if you get kills, you will start to snowball other lanes and your ganks will have more chance to succeed, so if you KS a bit early, this is not a big deal, but try to let the kills to your team-mates most of the time, specially if you see they are good players (if not better you get the kills than them).
The classic way to play Rek'Sai is pretty simpe :
You clear your camps, BUY A WARD OR TWO after EACH BACK that you will put around midlane (on top and botside) in order to protect your lanes from enemy ganks while you are not there and secure objectives. If the enemy jungler or midlaner roam a lot in your jungle, buy more wards and secure your camp, this way you will be able to make calls when he invade you and making him regret that.
Try to gank or counter jungle AS MANY TIME you can, when there is nothing special to do, FARM, Rek'Sai clear camp very fast, keep your levels growing. Do not forget that junglers unlike other roles, have NO LANE, if you fall too much behind your ganks will be weaker, you will have more chance to fail, but the more you farm, the stronger you will be, the most murderous potential you will be able to unleach.
How to gank
How to gank with Rek'Sai? Well, first, you must look the lane the most vulnerable to gank (not the most important, but the most vulnerable, remember that).
Keep in mind something : failing a gank is very bad for two reasons : First, it reveals your potion, the enemy jungler will know where you are and might go counter jungling you, gank somewhere else or take an important objective. Second, failing a gank means loosing time, loosing time means loosing farm, loosing farm means loosing levels and gold.
That's why you always want your gank to succeed, and for that to happen, you must prioritize the most vulnerable lane. How to recognize it? That's easy, look for the lane that is the most pushed, or where the enemy laners has the lowest hp, or lowest mana, or both of all that, when you pick your target you must do as proceed :
Check the bush with your red trinket, if there is a ward, destroy it, if not, then that's all good, you can gank. IF THERE IS A WARD and you destroyed it : MOST junglers think "ok it's over, he saw me" and just go away and already give up, the enemy laner know that, because few time he played jungle, he did like that. THATS WHY ME I DONT GO BACK. I know the guy think I will give up, you can guess from his way of moving if he expect you to be there or not. Sometime, I just wait few seconds, to give the illusion that I am indeed somewhere else. But instead, I stay in the bush, I watch. Then what to do? You must ping your opponent in order to give signal to your ally that you plan a gank. In most of time THE LANER MUST ENGAGE (expect if he is really low), some do not dare to, and often bad junglers engage first. THIS IS A MISTAKE, the laner must start to trade just before you start your gank, why? For few reasons :
First, it force the enemy laner to use his spells, using his spells will put him in cd, he might even, if he really fights back, use an ability against your team-mate that could have served him as an escape against your gank. Another reason : if you got spotted by a ward, the fact that your laner start the fight first, might focus enemy attention on him and not on the minimap, which means not on you... If enemy doesn't see you coming the gank has more chance to succeed.
If your team-mate absolutely refuse to engage, still try to gank, it might still succeed, but with less chance, just try and judge by yourself.
Often a gank doesn't result in a kill, but make the enemy laner flash, THIS IS WORTH, your gank is already a success, it might prevent him to escape against your ally next time if something gets wrong for him, BUT MOST OF ALL this means YOU MUST gank again. When you force a flash, COME BACK, now you know he cannot do this twice and if last time it saved him, the next time he will have nothing left.
I often gank back few seconds after a gank, often enemy doesn't expect it, think you are gone, and here you are, back again, expect that he has no flash, if he used a tp after your first gank and you and your ally have enough health, GANK AGAIN, killing someone twice just after he tp is just A DISASTER for his lane and a guarantee of snowball + this will make his team rage against him, and start to bring chaos in the enemy team synergy.
BUT HOW TO GANK WITH REK'SAI? So your team-mate engaged as planned, watch carefuly, not long after (but not too quick, watch with your eyes and decide the right moment), go in this way : always travel under earth, you have higher movespeed + possible vision of a potential counter gank if the enemy jungler is nearby + possibility to dash on your enemy.
Do not dash on him like a tard on a very obvious direction, this is a common jungle mistake of begginer. You must passively zone your opponent : go in the direction HE WANTS to run away to instead of himself. If the fight between him and your laner is going at his disadvantage, you don't need to move toward him, just stay between him and his tower, so he will not be able to back off, and will have no other option than flashing in your direction (or just die without flashing, which most low elo player never do, most of the time they will always flash even when they know they are dead) and getting BUMPED and die. Of course, this is a quite easy scenario, in most of the time you will have to really do your part.
Then once again, when you start to show yourself the enemy laner will start to run away toward his tower, try to go in the direction he is heading instead of rushing his position. It will naturally create a situation where the poor guy is just running toward you, this way you will make it a lot easier to reach him.
When you feel the moment right, just dash with your E, when he is bump activate your Q spell and your E as fast as possible, the ally laner should be helping you and very quick the guy should die, do not forget to use your smite to slow your opponent down in order to bump him faster. (If you need a bit more range to bump someone, just flash in, but do that only when you're sure it's going to kill someone.)
What about diving? Well, Rek'Sai can get through walls, so diving can be very easy, but do that only when you are sure to be followed, ping your intention before, write in the chat, make sure your allies understood your intention. If this is botlane, and there is a tank like Alistar or Braum, it's better if they get the tower aggro first by landing a CC. Anyway, diving from mid-late game is pretty easy with Rek'Sai as your build will be very tanky, early this is another story, you must always be very careful, do that if the enemy is low and has no or very few chance to escape, it's preferable to have a flash available in the case you got the tower aggro and need to disengage quick (giving a kill instead of picking one up would be quite a pity !)
But as always, do not loose your time with lanes that are always overextending. Try to dive when it's possible to, but you will always get some team-mate unable to freeze, spending all his match under enemy tower, risking to die at any gank, when you have a team-mate like that, no matter what he says, just tell him to freeze and if he refuses, ignore him.
But what to do when ALL YOUR LANES ARE PUSHING LIKE HELL? Then it is very bad, the enemy jungler will be really happy, the only thing you have to do is try to counter gank and counter-jungle the most you can (you still cannot really plan a counter-gank like you can plan a gank), so try to put wards everywhere, this will protect your team-mate and allow you to warn them if enemy jungler is going toward their lane. Also YOU ARE REK'SAI, drop few tunnels around the lanes that are overextending, like that if your ult is up, you can counter gank easily when the fight will start (this is one of the biggest strenght of Rek'Sai, remember it)
What are the most important things to get in a match? OBJECTIVES. Kills matter less, kills only matter because they can allow your team to take objectives, nothing more. When you get vision of the enemy jungler, or he is dead for instance, GO TO GET THE FIRST DRAKE. You are able to solo it early game after your first back, remember that, but be careful to not be spoted while you are doing it, coze this could result in your death + a free drake to the enemy team if you don't have time to smite. That's why you must always ward around when you are planning to solo a Dragon, and don't forget to use your red trinket and/or a pink to be sure no ward is spotting you. If everything seems fine go on and while doing so, keep an eye on bot and midlane in order to make sure nobody will try to stop you.
Always keep an eye on timers, ideally you should try to get every drake as much as you can the fastest you can, same for your red and blue buff (obviously, about your blue buff, give it to your midlaner, EXCEPT if he is a feeder, if he feeds ignores his complains and TAKE EVERYTHING NO MATTER WHAT coze keep that in mind : if he is goin 1/7, giving him blue will mean giving it to the enemy mid laner or enemy jungler, try to avoid that.)
When to do Baron? The enemy team got aced, or is in no position to fight back (low hp, no jungler, minions attacking their inhib etc...), then do it, remember that getting a Nashor will often means, if everything goes normal, winning the match, or at least take important objectives that will secure your win. Always make sure to have a ward nearby, in order to be able to know it if the enemy team plan to take it.
Another very important detail about Rek'Sai : SHE IS ONE OF THE BEST SPLITPUSHERS OF ALL THE GAME ! Why? She deals AOE damages, clear waves VERY QUICK et has very good base attack speed, which makes her very strong in taking towers and objectives fast. PLUS her ult is a free TP, allowing her to recall, buy an item and then come back right into the rigt in order to apply pressure on the map everywhere she can. Her mobility is great, she is able to detect enemies moving while burrowed and can dash through walls, this allow you to splitpush behind the enemy team quite "safely" coze you have great chance, if you do careful, to get away in time even if they try to punish you for taking their towers, just keep your eyes on the map.
We win this game mostly with towers/inhib and drakes/barons, keep that in mind and do not worry that much if the enemy team got more kills than your, if you're taking objectives and they don't, you will win, not them.
About your build
Before I used to build Rek'Sai like an AD Bruiser, getting a brutalizer, rushing Hydra, then sunfirecape, spiritvsage and finally last whisper. Then I realized this build might be viable, but is worth only if you are getting super fed. For a classic match, I suggest a more tanky build. Rek'Sai doesn't need that ad because she has already high base damages and deals even true damages with her E. That's why getting one (brutalizer) or maximum 2 damage items (malmorius, which provide you MR too) is more than enough. What Rek'Sai need is survivability in Teamfight, enough tankiness to dive a tower, a nashor, engage in teamfight, be focused and still survived etc... In brief : She is the FRONTLANE of the Team, your role is to engage teamfight, force the focus on you, rush their carries and slaughter them. If assassins manage to get behind you and start to attackyour carries, you must be there to protect them. All of this you can't do if you are not tanky.
Rek'Sai is a MONSTER, a terrible beast with heavy armor and high HP, see it this way !
That's why I really advice to rush SUNFIRE CAPE, this item does good damages early game, will improve your clear and allows you to dive and tank in teamfight quite early + if the match started bad and enemy ad carry is already fed for instance, it's good to already have armor (but if it's the other away, and that you get some horribly fed LeBlanc mid, then RUSH Lock of the Iron Solari, this will provide you Magic Resistance but also bring more survavibility to your team which greatly need it. Why rushing spirit visage or banshee veil when you can get an MR item that will not only help you but also your team? I really love Sunfire Cape and LOTIS on Rek'Sai, those two items + your jungle item make part of your core build.
Speaking about jungle Item, I obviously recommend Stalker's Blade Warrior, brutalizer is really nice on Rek-Sai, you will not build a lot of damage so rush this item, it will give most of the damages you will need for most of the game.
You still want to go damage? Then add an Hydra, but only if you are super fed.
About your runes
I tried a lot of different runes on Rek'Sai. I still think Flat Ad is the best choice, but let's have a look on other possibilities.
Rek'Sai, unlike Udyr, is not a runner but a dasher, once you reached your target with your E while burrowed most of the job is done already. You can still get those quints if you want to arrive EVEN FASTER in a lane or be able to get away easier while splitpushing, this is still a viable option, I just don't feel like I need them on Rek'Sai.
About your masteries
Go 21/9/0, this champ benefits a lot more from the offensive tree than the defensive one, you're going to build tanky items and stack a lot of HP that's why there is no need to go 9/21/0.
About the defensive tree :
Get 2 points in Enchanted Armor , DO NOT waste any in Block and Unyielding . Why? Because these two masteries provide you nothing as a jungler, they are indeed well adapted to laners early game (as they slightly decrease damages coming from Champions but do not have any influence on the creeps while Enchanted Armor does once you get some defensive items as it will increase your tankiness in general (therefore will be useful during teamfight as well).
5% increased bonus armor and magic resistance might not sound like a lot, but trust me this is going to get worth as you're going to build very tanky. Block and Unyelding are very early game masteries, they are clearly useful in lane but as you jungle, you're not going to lane against another champion, not going to get perma-harassed while you're trying to last hit. As you're not a laner, and will only get into fight briefly in order to get a kill for your team-mates early-game through ganks, you can ignore these masteries and take Enchanted Armor in anticipation of mid-game teamfights.
About offense, I highly no recommend you to get masteries like Spell Weaving and Blade Weaving . While those two will be very useful on a champ that spam his spells (such as Udyr or Skarner), this is not going to really express its potential on Rek-Sai as her fighting style doesn't work this way (CD of your E is relatively "long" + your Q spell counts as a boost to your basic attacks), it will proc however with your Bump and your nuke, but I don't think that's really worth as you will never reach full stacks, that's why I prefere to get 4 points in Sorcery as 5% CDR will help you slightly in clearing your camps and assist your ganks a little.
You can get Double-Edged Sword , I don't, but this is a completely viable choice, I just prefere to put a point in Dangerous Game which gives you back few health after getting an assist or a kill, why? Because this saved my life few time and allowed me to get mutiple kills when situation was getting very tight. Once again remember that 5% health is really going to mean a lot from mid and late game as you're going to stack lot of HP. The choice is up to you !
Do not get Expose Weakness , I love this mastery on junglers spamming their spells during a gank such as Zac or Maokai, but this is not going to be your case with Rek'Sai, so better ignore this one.
I already mentionned your role in teamfight, but let's state it again : you are the FRONTLANE of your team. Your job is to engage (first or second if there is another tank) with your E while burrowed and bump AS MANY champs as you can OR at least the carries, specially the one with no escape (a xerath for instance if he is at reach). Sometime you have to flash-bump, do not hesitate to if your team is right behind and ready to follow, by deleting enemy carries you guarantee your team to win the teamfight or can open the way to get a baron or a drake which will maximize your chances to be victorious. Do everything to force the focus on yourself, stun the enemy carries and dash away to protect your own carries if they are getting rush by a Vi, Rengar or a Shaco for instance.
Also even if you are frontline, enemy team cannot ignore your damages, YOU ARE REK'SAI, you can still deal horrible damages to enemy carries and you're AOE with Queen's Wrath is just OP in teamfight, rely on your damage, you will be amazed by the damages you will be able to deal with a very tanky build, do not rush ad items at all coast, you will see by yourself that a brutalizer + malmorius will be more than enough to destroy your opponents while with your 4K hp focusing you will mean wasting a lot of abilities for the enemy team.
Prey Seeker is not only a way to poke. As its name suggets, this ability allows you to reveal an enemy while you are burrowed in order to get vision on him which will greatly help your dash to succeed once your target is marked. You can also use it to check bush when you suspect a trap. Also, few people think about it, but remember that you can shoot a creep (like graup for instance), this will automatically activate their aggro, if an enemy is near, as you will get vision on the creep, she will start to move toward him, then it will reveal his location (also if a champion with very low hp flash or dash over a wall of the jungle in order to escape you, shooting a creep might make her finish him off and get you the kill, this is even more efficiant with Baron Nashor or the Drake :D)
Unburrow is definitely my favorite ability on Rek'Sai. This is YOUR MOST IMPORTANT ABILITY DURING GANKS AND TEAMFIGHTS because it works like a stun. Unburrow gives you a very powerful possibility to engage teamfights, if you bump several enemies while your team follow your move and damage them, this is going to be a slaughter (+ it triggers Yasuo's ult Last Breath, so if you've got a Yasuo in your team try to do that while he is nearby, this is going to create a powerfull combo. Of course, once an enemy is bumped, ACTIVATE QUEEN'S WRATH, you must take advantage that your opponent is temporary rooted to deal the most damages than you can while he got not chance to fight back.
This is also your best tool to counter assasins : Zed is using his ult Living Shadowon your adc? Stick to him while burrowed, at the moment he will emerge you can instabump him, which will prevent him to attack your ally and force him to back off or to die if he gets greedy. Also you can remains static next to his shadow after his ult, this will zone him out as he will not be able to back disengage after bursting someone, but if he does, BUMP HIM !
About Rengar's ult Thrill of the Hunt, this is the same logic : when you get notification he entered stealth mode, then he is for sure going to jump on one of your team-mates hoping to burst him down, in this situation act as a body guard : just stick close by to your most important carry (or the one that Rengar should be the most encline to jump on). AT THE MOMENT Rengar appear INSTABUMP him, same story as Zed except he can't disengage, you know what to do next.
Also, if a duel is getting pretty tight, always keep an eye on the circle around your challenger, when it disappear it means you can know him up again, for doing so, just switch your W twice and then try finish off your adversary. This technic saved me several time so do not neglect Rek'Sai kit, she is not just an auuto-attacker, switching between stances can make her a fantastic duelist very hard to predict !
Here the recovery time to bump an enemy after he got already knocked-up : 10 / 9,5 / 9 / 8,5 / 8 secondes
Tremor sense, one of the most interesting passive of the game !! This is what makes Rek'Sai so unique. This ability is a bit destabilizing at first (specially when chasing multiple targets) as it reduces your vision but enhance your awarness. Believe me once you get used to it this is going to be natural. Tremor sense can be a great way to counter jungle as you can get "vision" of any unit moving around, like that you are able to get know if the enemy jungler (or someone else) is moving through the jungle or farming a camp (this also reveal the creeps moves). But careful if someone is standing static in a bush, this doesn't trigger tremor sense as this ability only detect MOVING objects (which also include minions/creeps etc...), that is why when you get a doubt, you can fire Prey Seeker as a mean to scoot a location instead of face-checking it. You can still make the difference between a champion and a simple creep, as the blinking circle is wider for a champion than it is for a minion. Stay focused on the sound, when a moving unit is detected you will hear your sonar, that's why you must always travel burrowed, this will allow you to detect enemies before they notice you.
Another useful technic : The Tunnel Bait !
There is one very fun trick I just LOVE to use with Rek'Sai : the tunnel bait. You don't imagine all the kills I picked up this way !
How does it work? That's pretty simple ! As you already know, destroying Rek'Sai tunnels is easy, all it requires is to stand on it a few sec + getting one down gives a few golds. What people often forget is that's very dangerous !
Haven't I explained earlier in my guide that I enjoy to camp lanes and gank a second time very quick after the first time for the simple reason that enemies tend to think they are safe after escaping one gank. Well, Rek'Sai is really designed for that !
Let me explain, you made a gank, the enemy survived (maybe he even flashed which makes it even better !), then, obviously, your gank left its mark : there is for sure going to be a tunnel around the lane, most of the time leading right into it. Enemies have fun deleting Rek'Sai tunnels, they don't want her to TP back on it later + they like to get a few extra golds. This big tunnel lying around their lane tend to make them greed, they'r often going to attempt to destroy it. However what they don't suspect, is that you might be right behind, waiting for it.
If you see them walking toward your void gate, get ready, at the moment they're standing on it DASH IN by right clicking your tunnel, you will automatically pop out from the other tunnel just right where the enemy is and be able to bump him ! If you're laner is next to. The advantage of that is that you get a free dash while you have still the opportunity to dash again using your E Tunnel to enclose him if he tries to escape.
Sometime you can also use your ult Void Rush when a vulnerable (meaning killable) target is trying to get rid of your tunnel. Be aware that even if your tunnel is destroyed, this will not cancel your ult if you sarted to channel it before that ! Some enemies also ignore it and might not even try to get away, but for those that do you're still going to be able to dash again toward them so this is worth a try.
Pros / Cons
+ very Strong early ganks
+ Very Fast Farmer
+ Good AOE damages
+ Great splitpusher
+ Good Early, Mid and Late game damage
+ Give aditionnal vision to your team while burrowed
+ Free TP after level 6
+ Doesn't need mana
- Easy to kite for an adc (Vayne, Kalista...)
- First clear a bit tough and risky
- VERY WEAK before level 3
- Often Incite to flash and be greedy