Talk:Archangel's Staff/@comment-80.223.39.21-20121013093151/@comment-122.108.145.9-20121013101943

The stacking bonus mana is the unique passive. The mana-to-AP conversion isn't. With 5 AAS, you get a 15% mana-AP conversion. A lvl 18 karthus with 5 AAS (disregarding runes/masteries) has 1368 (base) + 2000 (flat bonus from AAS) + 1000 (from stacks) = 4368 mana, giving him 655.2 AP from the conversions alone. Add deathcap = (655.2 + 140) * 1.3 = 1033.76.

His ulti now does >1000 damage, his q does 800 damage to single targets, and his e deals 350 damage AoE.