Karthus, The Deathsinger

The vast quantities of magical energy that have been released during Valoran's numerous Rune Wars have scarred much of Valoran. Many remote locales continue to be twisted by residual magic, making them places where few dare to go. The Howling Marsh is one of these places, and the self-appointed overlord of this land is the lich known as Karthus. Some speculate 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. On the darkest of nights, Karthus is said to sing the tales of those who have succumbed to the swamp, past and present.Karthus has come to the League of Legends seeking personal magical power and influence. While not entirely as malevolent as an undead lich, he cares little for the consequences of death upon the living. Karthus can make the ground beneath his foes erupt, causing massive damage to those caught in the blast. He can create a wall of tangible pain, crippling foes who are foolish enough to pass through it. Being a lich, he feeds off the misery of others in two different ways either by defiling the environment around him or by feasting on the magical essence of those he fells in combat. Karthus may also sing the song of death itself; those who hear his baleful dirge are wounded to their very soul, and it is nearly impossible to escape this woeful aria.

Pros

-Powerfull caster
-Good ganker
-Can help, escape, chase people with "Wall of Pain"
-Great teamplayer

Cons

-He's very easy to kill
-Very weak against DPS
-Hard to play at the begining
-Characters such as Zillian, Sivir, Morgana, and Soraka can turn your finishing blow into a waste of time. The ultimate can be difficult to time out.

OR



-I use Teleport because, as this guide is meant for Karthus who is playing solo in a lane, it allows me to return to fountain to regenerate health and mana as well as make purchases without worrying that my tower will be pushed down while I walk up the lane.

-I use Clarity for mana goodness

x9 Greater Mark of Insight
Greater Seal of Vitalityx9 Greater Seal of Vitality
x9 Greater Glyph of Force
x3 Greater Quintessence of Potency

The only thing I feel really strongly about here is the magic penetration. You NEED magic penetration to be a formidable caster. No questions asked.

Lay Waste



This is your bread and butter skill with Karthus during early and mid game. It is a spammable nuke which has a minuscule cool down and does great amounts of damage, especially when you are able to single out one target in its placement. Use it early game to farm minions (one level of Defile makes killing a single minion with Lay Waste almost free of mana cost) and use it smartly to harass enemy champions. Used in combination with the massive slow from your Wall of Pain, this skill WILL land you kills.

Use this skill to:
~Harass (be sure to attempt to place the skill where it will hit the enemy champion apart from enemy minions)
~Farm (use it to easily last hit minions)
~Check brush (reveals area which the damage would effect)


Wall of Pain



Knowing when to use this skill is going to decide whether you are a chump or a superhero as Karthus. The slow is massive, slowing up to 80% of enemy movement speed at level 5. It reduces magic resistance and reveals a huge amount of map through fog of war and bushes. This is a great offensive and defensive skill. Practice and learn to use this skill to its greatest potential! Against a melee opponent who is rushing you, place it right in their path and force the slow/magic resist debuff and start burning them with your defile and kiting them towards death by slowly moving away while popping Lay Waste under their feet. Against those squishy ranged characters, cut off their escape with the wall and walk in to take them down with all the damage you can muster.

Use this skill to:
~Slow enemy champions sufficiently to easily place your Lay Waste as well as get in range with Defile
~Initiate battles. I have used the skill to open on enemy teams who I knew were "hiding" in brush. The huge slow and magic resist debuff makes those team battles much simpler for Karthus.
~Defend turrets. There are times in the game when the enemy team is throwing more at you then you can handle at the moment. Standing alone at a tower with low health and a few enemy champs trying to go through your pockets? Throw down a wall in front of them and the minions they are trying to tank with. The 80% slow and your Lay Waste damage should make them think twice about coming near you again.
~Escape/Save allies from being killed. The wall easily covers an entire lane of jungle path. Even with Karthus' limited mobility, slowing the enemy's move speed by 80% usually gives you time to get away.
~TO GET KILLS WITH YOUR PASSIVE. If you want to get those last few Lay Waste hits to get the postmortem kill, try laying down a Wall of Pain to keep them in range longer.
~To gain vision through fog of war. This still can be a great initiator both because of the slow and MR reduction, and also because it provides a wide range of vision. Use it over walls and in cramped jungle fights to gain awareness and battle control.

Defile



This is the skill that I see most misused by Karthus players. While the AOE active toggle from this skill does some massive damage, it burns mana fast. I sparingly use it to farm minions and only use it if I think the kill is at stake in early game fights. Far to often toggling the skill at the beginning of a fight leaves me mana-less quickly and unable to finish my kill or defend myself. However, grab a golem buff or some nice mana regen for mid/late game and let it burn away! It's like a miniature fiddlesticks ultimate when you get that AP and Magic Penetration stacked up high!
Very nice passive for staying in lane during early/mid game.

Use this skill to:
~Farm by grabbing last hits with Lay Waste early game without quickly running out of mana
~Farm mid/late game by toggling and walking through waves of creeps
~Destroy enemy champions

Requiem



While you will be criticized by enemy and sometimes ally for your use with this spell, don't be fooled by the simplicity of simply "hitting an R key". Playing a good Karthus and utilizing this amazing ultimate takes awareness of the movements of your allies and enemies.

Use this skill to:
~Initiate
~Push
~Discourage a gank in process
~Ensure kills that your allies cannot finish
~Disembowel your enemies and drive their confidence into the ground