Is this cooldown thing on Arcane Comet new?
While Arcane Comet is on cooldown, damaging a champion with an ability reduces Arcane Comet's remaining cooldown by 20% (10% for damage over time effects).
It's not highlighted on the google doc but I swear it wasn't there before.
Seems like just the thing DoT users need. Most DoTs tick more than once per sec so even at the reduced rate it's really good.