Deathbringer Stance (Aatrox Passive)

You empower yourself with the essence of demon blood. For the duration, once per turn, when you hit with a melee attack, you can deal an extra 2d8 necrotic damage. You regain hit points equal to half of the necrotic damage dealt by this effect.

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 2.