Selvis the Devourer

X: Destroy Target Creature you control, This Ability's Modifier becomes that creature's Toughness.
-5: Destroy Target Creature an Opponent Controls.You may activate that creature's First Activated ability for it's converted Mana Cost if it has one.
-20: Selvis the Devourer Deals 20 Damage to Every other Creature and Planeswalker, Then, you gain 1 Life for each creature that died from this effect.