Conqueror

Effect

Passive: Dealing damage to enemy champions generates stacks of Conqueror, lasting for 5 seconds, refreshing on subsequent damage against champions, and stacking up to 12 times. Gain 2 / 1 stacks for basic damage on-hit. Otherwise, gain 2 stacks for any damage that is neither basic nor non-pet proc damage, up to once every 4 seconds per cast instance.

Each stack of Conqueror grants 1.8 − 4 (based on level) adaptive damage, up to 21.6 − 48 (based on level) adaptive damage at maximum stacks, at which you also heal for 8% / 5% of the post-mitigation damage dealt against enemy champions.