Karthus

Middle

Rest in Peace

Massive damage scaling and kill threat.

Sorcery

Empowered abilities and resource manipulation

Summon Aery

Your attacks and abilities send Aery to a target, damaging or shielding allies.
The Ultimate Hat

Gain cooldown reduction and max cooldown reduction on your ultimate. This is increased further each time you use your ultimate, up to a maximum.
Transcendence

Gain 10% CDR when you reach level 10. Excess CDR becomes AP or AD, Adaptive.
Scorch

Your first ability hit every 20s burns champions.

Precision

9% attack speed, 10 ability power or 6 attack damage

Coup De Grace

Deal 7% more damage to low health champions. Gain AD/AP after kills or assists.
Presence of Mind

Takedowns restore 20% of your maximum mana and refund 10% of your ultimate's cooldown.

WhySummon Aery

Aery provides Karthus with reliable and repeatable damage output. When spamming [Q] in lane the extra bit of chip damage adds up to be an important factor in bringing the enemy to kill range.

WhyThe Ultimate Hat

Karthus' [R] has a massive cooldown so every point of CDR is that much more valuable. At max stacks your ult will be up 24s sooner.

WhyTranscendence

The extra bit of CDR from Transcendence allows you to opt into Magic Pen and raw AP in the mid game for more damage outout.

WhyScorch

Karthus' consistent damage output allows you to repeatedly apply Scorch on cooldown for extra damage and kill threat when your [R] comes up.

WhyCoup De Grace

Karth can make great use of Coup De Grace, synergizing well with both is [R] for executions, and when he's in his passive form looking to finish a target.

WhyPresence of Mind

Presence of Mind's mana and [R] refund is massive for Karthus. When paired with CDR and Ultimate Hat, a few kills/assists will greatly reduce your [R] cooldown for another fight.