The vast quantities of physical magic that were consumed and destroyed during Valoran's numerous Rune Wars have scarred much of Valoran. Many locations far from civilization have been morphed into hazardous and dangerous locales. The Howling Marsh is one of these places, and the self-appointed overlord of this land is the lich known as Karthus. It is thought that Karthus was a mage who, in life, was foolish enough to enter the fetid waters seeking his fortune, and that he was forever transformed by whatever dark magic permeates the swamp. Karthus now rules over his swampy dominion with an iron (albeit skeletal) fist. Visitors are not welcome, and those who are not scared away by the lich's terrible power most likely end up as one of the undead themselves... skeletons and zombies in Karthus' growing army of eternal servants. On the darkest of nights, Karthus is said to sing the tales of those who have succumbed to the swamp, past and present.

Karthus' tenure in the League of Legends is one of the more unusual ones in the history of the League. First, it is highly unusual that a lich who was known for isolation and hatred of life would even be a willing part of an organization which promoted the preservation of life. Next, Karthus specifically eschews the accrual of power and influence gained through service to the League; he is essentially an unpaid volunteer. This behavior is completely different than what his life outside of the League would have onlookers believe. Karthus has never spoken about his intentions in being a champion of the League, and in fact becomes quite agitated when asked about it. In the interests of not aggravating a lich, most sensible people subsequently drop the issue.

"Come visit my home, and I shall sing a dirge of your life as it once was."

• +Global ultimate with 1k damage on full build.
• +Great harasser/Spammer.
• +Good lane sustain if played defensive.
• +Effective 1on1 AND team fights due to overall AoE damage and Q mechanics.
• +Fun to play.
• +Deceptively strong with little spellvamp.
• +Don't fall being even losing lane.

• -Mid to end game squishy.
• -Mana hungry if played too aggressive or carelessly.
• -High Cooldown on ultimate.
• -Easy to kite if not played well
  

Lay Waste is Karthus main farming tool from level 1. Keep last hitting with Defile ready to keep your mana up. Every now and then place Lay Waste on the enemy path so he cant notice the difference between when you are about to cast for a minion or to harass effectively zoning the enemy.

*9 Greater Mark of Magic Penetration and 3 Greater Quintessence of Magic Penetration:
-With Arcane Knowledge gives Karthus 15|10% magic penetration, much needed to a properly early harrass.


*9 Greater Glyph Of Replenishment and 9 Greater Seal Of Replenishment:
-With Meditation gives Karthus +/- 26 Mana regen defeating early through mid game mana issues.

*3 Greater Quintessence of Revival
-Less 15% re-spawn time reduction allied to Good Hands can grant less 25% time spent dead which is great against high sustain champions like Morgana or Vladimir and give you more presence in lane.


* Greater Mark of Cooldown Reduction, Greater Glyph of Cooldown Reduction, Greater Seal of Cooldown Reduction, Greater Quintessence of Cooldown Reduction, Greater Quintessence of Scaling Cooldown Reduction and Greater Glyph of Scaling Cooldown Reduction:
-A full Cooldown reduction runes page gives 25.17% cooldown (with per lvl runes). With Karthus Lay Waste and Defile cooldowns being less than 1 second this runes setup will only be noticeable on Requiem having the ultimate up 40 to 50 seconds earlier.


* Greater Mark of Ability Power, Greater Mark of Scaling Ability Power, Greater Seal of Ability Power, Greater Seal of Scaling Ability Power, Greater Quintessence of Ability Power and Greater Quintessence of Scaling Ability Power:
-A full Ability Power runes page gives 55.62 AP at best. With Karthus AP ratios (0.30, 0.25 and 0.60) it means increasing Lay Waste and Defile damage by 17 and 14 respectively and Requiem by 33. I find that 10% Magic pen will grant more damage per hit than 55.62 AP.


* Greater Mark of Mana, Greater Mark of Knowledge, Greater Glyph of Knowledge, Greater Seal of Mana, Greater Seal of Knowledge, Greater Quintessence of Mana and Greater Quintessence of Knowledge:
- A full mana runes page will give 833.13 mana at best (with per level runes) giving only 46,285 at level 1. Having 20 + mana regen at lvl 1 its a better way to solve mana problems.


* Greater Mark of Replenishment, Greater Glyph of Scaling Mana Regeneration, Greater Seal of Scaling Mana Regeneration, Greater Quintessence of Replenishment, Greater Quintessence of Scaling Mana Regeneration:
- Greater Seal of Replenishment and Greater Glyph of Replenishment with Meditation already give enough mana regen and still save some space for magic penetration


* Greater Glyph of Magic Penetration:
- Greater Mark of Magic Penetration, Greater Quintessence of Magic Penetration and Arcane Knowledge already give enough magic penetration for early game. Buying Void Staff will compensate for enemies stacking magic resistance from mid to end game.


* Greater Quintessence of Movement Speed
-Having no escape mechanism or movement speed itemization those (max) 4.5% movement speed wont make such a difference.


* Greater Quintessence of Gold and Greater Seal of Gold
-Being one of the easiest champions to farm with, the need for this 2.625 more gold per 5 seconds is highly debatable.


* Greater Quintessence of Spell Vamp
-A well played Karthus should buy Health Potions to maximize his lane presence. If you have trouble staying in lane just buy Hextech Revolver before the Rabadon's Deathcap.



*Pretty much everything not mentioned before, from Greater Mark of Attack Speed to Greater Seal of Lucidity for obvious reasons. Even magic resistance can be considered useless with this build and play style.

Mental Force - Being a glass cannon this is a must have mastery.
Sorcery - Having a 200/180/160 seconds cooldown ultimate, every bit of cooldown reduction is good.
Arcane Knowledge - 10% magic penetration for a proper early game harrass.
Havoc - 1.5% damage increase will give that extra edge late game when you usually deal around 4/5K damage throughout a team fight.
Blast - Again, this is a glass cannon build Karthus.
Archmage - And again the glass cannon oriented build.
Executioner - Karthus is supposed to use his ult when the enemy is below 40% health, usually even below 10% so this 6% more damage will help to assure the kill.




-Personally wont recommend any points on defensive masteries because, after all, this Karthus is supposed to be a glass cannon, although Rod of Ages is a must buy item its purpose's to provide early game durability and its overal purpose is better explained on Items and Gameplay sections.



Summoner's Insight - Out of better choices that 15 seconds less cooldown on Flash is the only viable option.
Good Hands - Proven very useful to have a better presence in lane even dieing more than normal.
Improved Recall - Out of better choices that 1 less cooldown on Recall is the only viable option.
Meditation - Very useful mana regen early game.
Runic Affinity - 36 seconds more on every blue.

Starting items:

Core build:

Full build: