A fun build that actually works for both ranked and trolling normals (dont troll ranked, if you do that, you are a bad bad person). I played Karthus a couple of times and he is definitely one of the most game/teamfight changing monsters in the game (right on with par with a good Cho Scream/Rupture combo, a Malaphite knockup initiate, Ashe Arrow initiate Pantheon or GP zoning blast ulti or a good Amumu Curse).
And he is the only hero that attacks with popcorn, pink snakes and red space lasers... well maybe the 2nd that uses space lasers but you get my point.

http://www.youtube.com/watch?v=afiNqahGICU - he is also so cheezy that a sleeping brit can play him since he is never gonna give him up and never gonna let him down - http://www.youtube.com/watch?v=Y-hQ1Iai5aY

Sorry for lazy drawings or lack of real game images, when i try to screenshot something in game it starts jumping like crazy...

Pros - you are a lich lord of a swamp with pink snakes, popcorn and space lasers, what more do you want? Ahh fine here is a good list:
+ You can take any lane in a solo que because of zoning and farm strength
+ Is a pretty good carry/massive damage dealer even if not fed because of post-mortem AOE
+ Tanky and hes slows on everything
+ Changes teamfights even if half a map away
+ You can die 4 times before actually being dead?

Cons - OMFG noob Karthus stealing my killz for my super epeen and KD ratio! Feeder! OP, haxer easy mode! No, now seriously he has some weakpoints:
- 3 items made to counter you
- Weak to silencer enemy
- You will get focused a lot
- No escape mechanism/good reliable CC without wall of pain
- You could end up underfeeding your carry if you take all of his/her kills
- Dying could be seen as feeding if you dont take at least one or two enemies with you (your ratios should be like 1.1x/1x/2.7x), you are always better off with loads of assists than kill streaks or taking kills a carry could have obviously gotten
- Might get yelled at if your team already has a AP carry (don't worry you can go solo top)

Runes are all personal preference but i found that this setup gives a nice amount of both early game power and late game annoyance (2 Greater Quintessence of Revival really help post 40 min when your revive is on cd, but 3 were overkill).

4 Greater Seal of Vitality will let you stay a bit living but feel free to swap them for Greater Seal of Health if you want more early game hp or more Greater Seal of Replenishment if you find yourself out of mana more often (what you shouldn't because of the masteries but who knows how much you spam your popcorn.

Greater Mark of Magic Penetration is a no-brainer on caster but you could swap 3 of them for Greater Seal of Attack Speed to get about same timing on lay Waste and auto attacks (popcorn first and aa right after).

Greater Glyph of Scaling Cooldown Reduction was also kinda a no-brainer because of the cooldowns Karthus has and in combination with masteries puts Karthus later on 18$ cdr what in combination of blue buff (that you should try getting as much as you can) gets you to the cap.

But I'll say it again, runes are all personal preference and their effectiveness is dependent on your playstyle.

While some people may argue about going offense for more damage, utility gives you far more, well utility and general disruptive ability.

- 4 AP is 4 AP what more to say.

- The native power of Brits and lets you cast stuff a bit more often.

- Ignores bit of MR early on and a ton later, works against pesky tanks with their Banshee's Veils and Forces of Nature.

- Same reason why I took Greater Quintessence of Revival, they are about a 5-7 second off your death time.

- 1 second may not seem a lot but when a friend is in need or dragon being taken it could mean giving the enemy 200-900 gold just because of a channel (and it lets you teleport out of a really bad situation faster)

+ - you can spam more popcorn on the enemy and a bit more mana (you should have 12 mana/5 at level 1)

Not really worth it but it lets you get to the next tier and gold is never a really bad thing.

- just put a point in it since i needed to get to 20 points and more exp doesn't hurt.

- 2 points for 1/2 pots early on (depending on how long you say in base), yes please. Starting with a HP pot and Dorans is so strong on casters i cant express how happy i am for it to be possible again, you will have good sustain, nice chunk of hp and starting AP/mana regen = almost secure early lane dominance and even lets you go solo top if a anti-melee unit is there and needs to be zoned (but dont try to lane against a Cho'Gath with this build, he will have the upper hand no matter what).

- 6% cd in combination with the 4$ from before, MORE POPCORN AND LASERS!

- the thing that lets this build work in conjunction with Karthus even on Ranked games 15% off Revive (459 seconds CD down from 540) and Teleport (255 seconds CD down from 300)

- Creates a delayed blast at Karthus' cursor position. After 0.5 seconds, deals 40/60/80/100/120 (+0.3) magic damage to each nearby enemy, this deals double damage if it hits only a single unit.

AKA Popcorn, maxed first for farming and damage, try a few games vs a friend that is good at juking on a custom map to get acquainted to leading the target and predicting enemy movements. It is seen through the fog of war as long as its red dot isnt covered by a creep or inside Brush, so be careful when using it since it may give off your location.
It will be considered as a single target spell if it only hits one enemy so it has nice synergy with Rylai's Crystal Scepter


- Creates a 800/900/1000/1100/1200 distance wide wall at target location that lasts for 5 seconds. Enemies that pass through the wall have their Armor and Magic Resist reduced by 15/20/25/30/35 and Movement Speed reduced by 40/50/60/70/80% for 5 seconds (their Movement Speed gradually recovers over the duration).

The only real escape mechanism you have so I take it at level 2 if the enemy has a jungler, if not feel free to take Defile for more mana sustain.
Anyways, having rank 1 before 6 and rank 2 of Wall of Pain at level 8 is a must.
Its debuff works on Baron and Dragon and it reveals a pretty big area around it so if your mid or bot lane use it to check on dragon pr even baron if a ward passed off or the enemy went MIA/SS in a fishy manner (Fizz not included since he is always fishy).

- When Karthus kills a unit, he restores 20/27/34/41/48 mana.
Upon activation drains 30/42/54/66/78 Mana to deal 30/50/70/90/110 (+0.25) magic damage to nearby enemies each second.

Mana regen and AOE snake dance spell, remember to toggle it on just before initiations and in fights and leave it on as long as there are at least 2 enemy champions inside it, they may not notice but a Wall of Pain+ Defile combo will bring any enemy under 2k health down really fast. With blue you can hold it up almost forever.
Don't use it for farming unless there are 3 minion waves pushed together or you have blue buff, it will just drain your mana


- After channeling for 3 seconds, Karthus deals 250/400/550 (+0.6) magic damage to all enemy champions (regardless of distance).

Just as the name says, its the mass of the dead (enemy champion corpses).
It hits everything strong enough to kill you that the enemy has and can change teamfights into your favor. The optimal thing to do before a teamfight is to charge in Defile on, Wall of Pain as many people as you can, place popcorn as much as you can, die, (if revive is up) place more popcorn and another wall while having defile still on or (if revive is soon off cd) use requiem right after you placed a wall at the most obvious enemy escape path, dont use it alive within 900 range of a enemy that can interrupt casting!
During the mid game use it to help fights on the other side of the map and picking off fleeing low level targets, map awareness and communication are the key (as the other players to call KU or Kult or ping 2 times or at least something like that if a enemy escaped them that has at least 40 less hp than your current ulti damage). Use the minimap and tab screen to judge if the enemy can survive if you are blindly using it. And if they try to counter it, the enemy is more likely than not altering their build just to be safe from 1 of your deadly spells (some people dont even know that your inanimate early game enemy, Hexdrinker, exists).

For short all of them are here to make the enemy rage, while crawling around you, why you just took 50% of their whole team by doing nothing but walking and throwing popcorn (or just standing there stunned eating 3 or more ultis).

Just check the item purchase list if you dont boring want explanations or some small guidelines, but if your to lazy to scroll here: , , , , ,

You should start of with stronger lane presence with the Doran's Ring, since you dont really hold it (but must give off the aura that you are stronger than the enemy) because you will get your first AP item between levels 6 and 9 after you popped your ulti once or twice to pick of a kill or assist and went back. Going for a early Rod of Ages will let you tank a few hits and you wont have problems with Veigars if you rushed for Rabadons or Archangels. If you are in a lane against Morgana or Annie feel free to go back 2 times before level 6~7 to get Catalyst the Protector and a Amplifyng Tome (you do get it either way when picking up Rod if you had at least nice farm or got a ulti kill/assist).

Then upgrade Boots to the one fitting the situation (if you find yourself missing a second or so on Wall of Pain take CDR, if you want more damage go for Sorcerer's, enemy full of CC, feel free to go Merc Boots).

Note: During the lane phase dont forget to use your auto attacks for last hitting too, the animation may be bad but it deals nice damage.

What Giant's Belt right after Rod of Ages? Well yes, more hp is more time you can spent on the field with your 2 snakes dancing on the enemy and placing bombs, and it makes you pretty much a second tank or at least nice damage sponge.
After Giant's Belt feel free to go either a Blasting Wand or a Tear of the Goddess depending on what you feel is needed and then pick up the second one after it (i usually go for Tear since you get to stack up the mana earlier.
Sell Doran's Ring and pick up Rylai's Crystal Scepter after you got the second item.
It gives you 2 massive AoE 15% slows and a 35% slow if you hit only one enemy with popcorn that adds to your wall of pain slow (they will crawl).

Now its about level 16-17 and time for you to get the heavy hitting blasters ready since its Rabadon's Deathcap (you should have at least 5 assists and 1-2 kills by now or you are using your abilites and summoner spells in a wrong way).
After getting the Deathcap, its time to improve your Penetration to 50% with Void Staff!
And then for the last bit of pain, get a Archangel's Staff with your 2.7k mana!
After that just buy Elixir's.

DONT FORGET TO WARD DURING THE GAME! Buy a Sight Ward, stop a gank, save a life!

Optional Items
I dont really think that they fit revive teleport karthus but here are some other solid items:

- nice spellvamp, sustain, 80 ap and sharing 30 to your pals... nice but most of your spells are aoe and popcorn will most likely be cast while there are 2 enemies. Feel free to pick it up early and sell it later, its just i dont find that the 150 hp you gain from a rank 2 ulti is worth it and it sure as hell wont revive you from your ghost form - Swap for Rod of Ages or Archangel's Staff

- good cdr and mana regen, nice active (usable even in death form), but you wont need them since your role is not so much burst but high sustained damage, and you hit cdr cap with blue buff.

- trollface.jpg

- Great item, but i find the benefits of being a 2 second golden statue of a statue kinda redundant and the whole point of revive teleport Karthus is that the enemy focuses you before your friends if your missing a real tank... or just for lolz to troll the enemy and make them think they used their ultis on a good target - take it in place of Rabadon's Deathcap

- Pretty much the same as Hourglass, i find it not really worth it for this kind of playstyle - take in place of Void Staff

Note: Hourglass and Abyssal will put you at 6000 effective health, but 487 AP, while Rabadons and Void Staff give you 680 Ap and ignoring 46% of enemy magic resistance on 4500 effective health. So depending on how tanky and how fast the enemy can get away from you, they can end up being more effective (both Effective health numbers are counter looking at enemy having 9 armor penetration marks and 9 magic resistance penetration).

- its op against split pushing/backdooring teams, great for your farm and exp, all while helping you secure dragon if the jungler is smart enough to ward it.
And lets you jump right into the action after resurrection.

- Bad Summoner spell for everyone except you and pantheon, actually its even not so good on pantheon or is it just to op for you? Ill never get that right, but whatever, it lets you come back a second and third time every 7 Minutes of the game with more hp for some time. Time it correctly, try not to die, but if you know the enemy will kill you right there, just charge in unload everything and rez back if your ulti got up just after you perished.
Again DONT use it for lolz and dont be suicidal early on, it can save your team (and the game) if the enemy is pushing or they just got baron.

Honestly you can pick any summoner spells you want, its just that Revive and Teleport are kinda the point behind the Suicide Revive Karthus playstyle.

Both of them need good timing and positioning, using wall of pain can and will save your friends when running away by placing it across a choke point.
Using Requiem should be from a safe position (where the enemy cant interrupt you) and always in death form if you dont have revive up (you have a second to place a wall of pain before that).

If you zoned the enemy out of the lane with popcorn, while on over 60% hp, go gank a lane in need, use Wall of Pain from a brush or out of the fog of war to surprise the enemy (its long range and size give you a nice margin of error) and can make them take the river rout or pop flash so that they dont lose half their speed and a nice chunk of resistances.

Tower diving is only a option if you asked your allies or they have long range ultis (Ashe arrow, Lux/Ezrael sparkle beams, Caitlyne snipe...), but if you are caught under the enemy tower, try to block off all their escape routes using your Defile and Wall of Pain
After level 11 you are pretty much free to roam a bit around as long as you hold your level up to the enemy carry

Junglers

- your best friends, worst enemies, people you can pick up with good timing and wards... or the dude that will be the bane of you laning phase.

Enemy junglers that stay on low hp: Amumu, Rammus, Olaf, Shaco
They are almost all the time on pretty low hp during their jungling tours so a quick ulti from level 6 to about level 12 can make them much less useful.

Ally junglers that will ensure get in combination with your wall: Warwick, Shyvana, Olaf, Udyr
Some guys may need help in the initiation and the wall gives them all they need, but i felt that this 4 need special note since they deal mixed damage with their abilities what makes your wall that much more worth for them.

I have only listed enemies that will make your laning phase at least really really hard.

- You guys are old friends from times of doom and disaster, but he will just get you with his scream, rupture and spike AOE. Most good Cho'Gath players will take Boots + 2 hp pots and one mana pot to zone you, your popcorn wont deal that much damage because of his massive hitbox as long as he stays near his minions and he will regen any damage takan with his passive, your only hope will be that your jungler notices your cries of help and ganks before level 6 or that you catch him in a bad position and just wall/popcorn zone him.
Later trough the game, if you want to use your ulti, stay about the full normal vision range away from him so that he cant rupture your ulti.

- High early game damage, 2 blinks in a short time, will kill you if you get close enough to her, ask your jungler for a few scare runs (you dont actually need to kill her just make her waste a flash or go back to base) and try to outfarm her from a nice range. If you manage to hold up to getting Catalyst the Protector and Boots without a death (level 6 if you got a assist via ulti) you can start opening up and going into the offensive.

- I dont really see her as a hard enemy to lane against because even if she went boots first, all she does is pretty slow and mana costly, so id say a few well placed popcorns will bring her into egg form. Just dont take things like ganking or getting her killed to high up on your priority list, farm and you'll be fine (remember to get Merc Boots against her).

OR - Both can outfarm, zone, harass or even just plain kill you, but both also need good positioning for it. Against Annie, stand about a cursor size away from your caster minions, against brand stand directly counter to him and use popcorn to hold him in one edge (he may thing you are missing, but just pop a few if he wants to go left so that he is in a line with you) and always dont run straight away from them, use kind of zig zag movements to escape. Brand will often place a Pillar of Flame a bit behind you so getting closer to him with defile on will ensure you a nice safe zone while escaping damage.

- Your worst nightmare, since Karthus has a pretty big hitbox, her Dark Binding may hit you even trough it shouldn't, Tormented Shadow melts your minion protection and her Black Shield gives her the chance just to walk trough your only defense without any debuff. Farm as hell and hope that she isnt also building a Rod of Ages.

- Long Range, can stay in lane forever if he went with Meki pendant and HP pot, pain in the arse, get boots as soon as you can, wait for him to get into static form and learn to move left and right when escaping instead of running back. If your on under 600hp and he hits 6 run as hell and port back from your 2nd tower or just walk back... or you die and you wont even be able to see him or use your lich form effectively.

Overall a semi troll, semi ap caster build with anti-christian tendencies.
Here are some chibi karthus jokes (from ask karthus requiem time):