Talk:Karthus/@comment-93.186.16.212-20120904052641/@comment-4184629-20120904160425

Generically, in a 1v1 you kite, launch Q's and try to keep at least a minion between you and them (usually to stop those with skill shots, and of course, you won't always have minions). If they have a lot of health start with W and hit them with Q a bunch. If they don't run away, cool! Keep this up until they give up or they are low then follow up with a W (if they have lots of health then hopefully wall will be back up by now) activate E and keep using Q on them. If they manage to run away and are low enough, use R.

5v5, prefight keep launching Q and running away. Once the fight starts (or if you are starting it) lay down W activate E and walk closer continuing to use Q. Obviously the teamfight requires coordination so you don't die walking into them while your team just sits there. If you have Zhonya's you should activate it either at the start of the fight or when you are low on health. Continue to fight with E activated and Q's (W when it comes off of cooldown but teamfights usually don't last that long) until you either a.) die b.) kill the entire enemy team c.) they retreat d.) you run out of mana. When you die you should usually ult to help finish the fight (though if your team got obliterated and they all have a good amount of health, don't bother). If they are retreating and had low health, ult; they didn't have low health, don't ult save it.

Build I used for awhile (not what I use all the time anymore since they increased the cost of WotA): Mana crystal, health potx2 > Tear of the Goddess + Boots > Hextech revolver or Catalyst the protector or Sorceror's shoes or Needlessly large rod (depends on survivability needs) > followed up by whatever item is built from those (if boots go into WotA as your E and Q will be giving you more health from the magic pen and your ability to catch up to someone should be equal or better). From there build into whatever, prioritize Rabadon's but it can be put aside for survivability. Final Build: Archangel's Staff, Sorceror's shoes, Rabadon's Deathcap, Will of the Ancients, Zhonya's Hourglass, and an AP or survival item of your choice (good picks are RoA, Banshee's Veil, or Rylai's (not a fan personally because of the lack of mana, but it can be very helpful in hitting successive Q's)).

TL;DR 1v1, use your Q at a distance until they are low enough to engage. 5v5, W into E into QQQQQQQQQ, die R. Build = Mana then damage or survivability then the other of the two then you are become the destroyer of teamfights