I'll do the same introduction as before. I'm PH45, and welcome to my Kayn guide! I am a top lane main, who plays jungle from time-to-time. I finished Diamond 5 in Season 7 and Diamond 3 in Season 8. This guide will give you some insight on Kayn, Kayn's abilites as well as how to play him in general and how to be succesful with him!

Pros + Can gank from places that most junglers cant that easily + Has a ult that makes him untargetable + W is good for laning harass + Has good clear in jungle + Becomes very tanky and sustained when the darkin + Has 2 different forms so basically 2 champs double the fun :D + Q can also be used to dash over some walls Kayn is a very mobile champion who excells at dueling and helping teammates after he has gone through his transformation.

Cons - Isn't that great early game in terms of damage - Requires transformation to become truly strong - Shadow Assasin can feel lacking against tanky teams - Awkward to play if you can't get the transformation near ~10 minute mark -Pretty low range - Once you choose a form you can't change - A Feast/Famine type of champion

For the primary rune tree I picked Domination. It gives Kayn a bit more damage output and a bit of healing which all are nice for him especially later on.

More burst damage, which is a solid choice for any assassin. More reliable than Dark Harvest, which is why I prefer this.

Sudden Impact is great since you get to proc it in most fights thanks to your Reaping Slash, giving you a bit of extra pen to make you deal that slight extra damage which might make the difference in some cases.

Both of these are fine choices but in the end Eyeball Collection will probably benefit you more if you manage to get a lot of champion and ward kills. If you feel like you necessarily won't be getting that many kills Zombie Ward is a great choice as well as it gives your team much more vision with Zombie wards.

Ravenous Hunter is a good source for sustain. Sure Kayn has a bit of it built into his Shadow Step, but in combat this can heal up a pretty decent amount especially later. Other choice is Relentless Hunter which might be a great choice if you plan on going Assassin form since you'll have even more mobility.

Sorcery has good choices for Kayn that grant him extra mobility, which is important on him due to utilization of Shadow Step.

Waterwalking is extremely good for skirmishes and fights at the river for Dragon/Baron etc. You also get a bit of damage when this rune is active which is nice for those skirmishes.

Celerity overall just fits nicely with Waterwalking and also with Shadow Step since both grant movement speed. this naturally boosts those a bit.

• The Darkin Scythe (Passive): INNATE: Dealing damage against champions causes them to drop orbs that are automatically collected upon leaving combat, filling a bar above Kayn's portrait. Post 15-minutes the amount of orbs is reduced.
  Once the bar is full he can choose to either be overwhelmed by Rhaast or win over Rhaast and become the Shadow Assassin based on whether he has damaged more Melee role melee or Ranged role ranged champions, respectively. Once primed, the other option becomes available after 4 minutes. When he has finished collecting orbs, he can keep fighting to collect orbs for the other form instead of waiting around for the full 4 minutes.
  The transformation can be activated only while standing in the spawn fountain.
  Shadow Assasin: Kayn's basic attacks and abilities deal 12% - 44% (based on level) of post-mitigation damage as bonus magic damage, lasting for 3 seconds upon entering in combat with an enemy champion, refreshing after 8 seconds out of combat with them or by using Umbral Trespass.
  
  Rhaast heals for 30% - 40% (based on level) of the post-mitigation damage that he deals with spells against enemy champions-
  
• Reaping Slash (Q): Kayn dashes forward, dealing physical damage to all enemies he passes through before flourishing his scythe, dealing the same damage again to surrounding enemies. Other abilities can be queued while casting this ability. The ability also deals 40 bonus damage against monsters and minions no matter which form Kayn chooses.
  
  With Shadow Assassin form the skill is unchanged.
  
  With Rhaast both instances of Reaping Slash's damage are modified to 50% AD (+ 5% (+ 4% per 100 bonus AD) of target's maximum health) physical damage, capped against monsters.
  
  
  
• Blade's Reach (W): After a short delay in which he can't perform any other actions, Kayn performs an upwards sweep with his scythe, dealing physical damage to all enemies in a line and slowing them by 90%, decaying over 1.5 seconds.
  
  In Shadow Assassin form Kayn conjures a living shadow at the casting position to perform Blade's Reach in his stead, allowing Kayn to perform other actions. Blade's Reach also gains extra 200 range
  
  Rhaast makes Blade's Reach knock up enemies for 1 second.
• Shadow Step (E): Kayn gains 40% bonus movement speed, is ghosted and can ignore terrain collision for 1.5 seconds. Immobilizing effects will interrupt Shadow Step.
  Kayn heals himself upon moving through terrain for the first time and, if he's not in combat with enemy champions, Shadow Step's duration is increased. Entering combat with a champion after the effect is enhanced reduces the remaining duration to 1.5 seconds. The effect also cannot remain active out of terrain for longer than 1.5 seconds.
  
  Casting Shadow Step as Shadow Assasin removes slows, additionally if Kayn enters terrain at least once, Shadow Step will be improved for the remainder of its duration to grant 70% bonus movement speed and make Kayn immune to slows.
  
  With Rhaast Shadow Step remains unchanged.
  
• Umbral Trespass (R): PASSIVE: Kayn basic attacks and abilities against champions apply Umbral Trespass for a few seconds.
  
  ACTIVE: Kayn infests a marked enemy champion for up to 2.5 seconds, revealing them and becoming untargetable for the duration. Reactivating Umbral Trespass ends it earlier. Upon reactivation or at the end of the duration, Kayn wrenches himself free from their body in the cursor's direction, dealing physical damage to the target.
  
  With Shadow Assassin Umbral Trespass gains 200 bonus range and emerging from the target resets The Darkin Scythe cooldown. As Shadow Assassin Umbral Trespasses exit dash also gains some extra range.
  
  With Rhaast Umbral Trespass's damage is modified to deal 10% (+ 13% per 100 bonus AD) of target's maximum health physical damage, and heals him for 70% of the pre-mitigation damage.

Items depend on which form you go. Shadow Assasin goes for more pure AD items rather than tanky ones while Darkin Rhaast wants more tanky and survivability items while still retaining some of those core damage items.

Skirmisher's Sabre This is the one you take when you choose Rhaast. Later on you can duel much better those tanky bruisers and opponents who you otherwise couldn't and early on it also is nice amount of true damage.

Stalker's Blade Enchantment: Warrior seems to be best pickup for Kayn when you go Shadow Assassin. You can catch people even faster and also in general just lets you burst them really fast.

Black cleaver Another perfect item for Rhaast. Let's you shred your opponents armor and gives you AD and health.

Spirit Visage One of the best items for Darkin form. It increases your already good healing and it also gives you magic resist and health so it's a perfect item to get as the Darkin.

Death's dance Death's Dance is an amazing item for Kayn In the Darkin form as the 30% damage turn into bleed is a big help as it allows you to heal back up while the bleed damage is applying to you. Also the healing portion of this item is incredible combinded with already great healing in the Darkin form + Spirit Visage synergy.

Duskblade of Draktharr This item works well with Kayn's ultimate since you are unseen for a small time. It slows your opponent and deals a nice chunk of damage.

Guardian Angel It's a nice item to get especially later on in the game when dying becomes more and more costly. Gives you nice amount of damage and also let's you revive once.

Ninja tabi Good vs autoattack reliant machups. Also if the opposing ADC is fed. I pick these most of the time unless the enemy team has heavy CC in which case you should go Mercury's Treads.

Mercury's treads Pretty self-explanitory, get this if the opposing team has a lot of CC as it can shut you down pretty well.

Thornmail This item cripples enemy AD champs with healing since it now applies Grievous Wound on the champs that attack you. Also gives you some HP and armor and also applies Cold Steel which is nice.

ITEMS WORTH CONSIDERING:

Trinity Force Trinity Force could be a nice item in some cases for Kayn. It gives a lot of different stats. It gives a bit of mana which Kayn can use, Sheen proc is also nice and also some tankiness so that you don't get bursted down. However Kayn doesn't autoattack that often and thats why I feel Black Cleaver is much more optimal but in some cases Trinity Force could be considered.

You want to max R>Q>W>E usually. If you are laning in top or mid vs ranged or even in some melee matchups I feel like maxing W will pay off more.

So Kayn has two different forms he can transform after a while. If you fight melee champions more you can transform into the Darkin Rhaast, who is more of a bruiser/tank like fighter with insane healing. If you go toe-to-toe with ranged champions you can transform into the Shadow Assasin. You can also wait 4 minutes after a transformation has been unlocked if you desire the other transformation instead. You should always gank when possible, to get your form faster since it's a huge powerspike to get your form, especially during early game.

The Darkin Rhaast form is more of a bruiser/fighter style of a form who greatly benefits of tanky stats. I tend to build mostly tanky but still getting some damage items so that I can still fight opponents and possibly even kill squishies alone.

Shadow Assasin as the name suggests is an assasin form, wanting to assasinate the squishies of the enemy team. Late game though I feel many champions for example like Malzahar can shut this form down easily and he isn't as viable in some cases. They also made Shadow Assassin's Shadow Step to have an 8 second cooldown at all ranks so his mobility is really high

I feel the Darkin form is more versatile and works much better against diversity of comps rather than Shadow Assasin. Shadow Assasin feels lacking while Rhaast can go with his healing 1v2 or 1v3 while his team is catching up. Shadow Assasin can work against a very squishy comp but most of the time I will just get the Darkin form since it feels much stronger and tends to work out very well even if the transformation is a bit delayed.

I'll go into more depth about the benefits of each form in the ability section.

Shadow Step allows you to gank more easily for example from enemy jungle walls etc. You can also use Shadow Step + Flash into a wall to get out of sticky situations. Also you can do Shadow Step + Reaping Slash to dash inside the wall to escape sticky situations. You can also get over some narrow walls with only using your Reaping Slash.

Jungle clearing is changing a bit during Season 10, overall more paths are available. As Kayn you can do a lot of different paths, and this is one that has been staple for a while: Red buff -> Golems -> Raptors -> wolves -> check if you can do scuttle -> blue buff -> gromp -> after that you can either look for a gank, or if it isn't possible recall to buy.

You can also just clear for level 3 and then try a cheeky gank since you can just pass through walls and potentially force your enemies Flash or even kill them if you get a gank from good position and your teammate can lock your gank target down.

I'll add here gameplay clips when I get something upload worthy with Kayn
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Kayn is a champion who can really make a good use of his transformations powerspike if he can get it early. If it's delayed then it isn't as good but it can still work out perfectly fine. His weak early game is compensated with his strong mid to late game. Any feedback on this guide is highly appriciated, I will be updating this constantly whenever there is something to update or new ways of playing Kayn. Have a great time infesting and reaping your opponents as Kayn! And of course if you enjoyed the guide make sure to subscribe on YouTube for League of Legends content! Subscribe Also some of the code used in the making of this guide is from http://www.mobafire.com/league-of-legends/build/making-a-guide-101506#chapter11 @jhoijhoi - PH45