Ray of Enfeeblement

Target creature gets -4/-0 until the end of the turn.
If the creatures power reaches 0, it is destroyed.

Mythic {b}{r} (You may cast this for its Mythic cost. If you do, the effect becomes “Target creature gets
-6/-0 until the end of the turn. If the creatures power reaches 0, it is destroyed and it’s controller loses life equal to its power before the spell was cast.”)