Aurora

Innate: Aurora's damaging basic attacks and abilities apply a stack of Spirit Abjuration to enemies for 4 seconds, refreshing on subsequent applications and stacking up to 3 times. The third stack against a target consumes them all to deal bonus magic damage equal to 1% (+ 2.7% per 100 AP) of the target's maximum health, capped at 90+10*x (based on level) against monsters.
Upon consuming the stacks from a champion, Aurora additionally exorcises them, freeing a Spirit from the target that follows her for the same duration. For each active Spirit, Aurora is healed for 2 + x (based on level) (+ 2% AP) every second. Subsequent exorcisms free further Spirits and refresh all active Spirits. Aurora may have up to 4 Spirits at a time, for a maximum heal per tick of (2 + x)*4 (based on level) (+ 8% AP).