Binder of Cruel Life

Whenever you cast a spell using its Cruelty cost, create a 1/1 black Skeleton creature token.
Whenever you cast a spell using its Necromancy ability, create a 1/1 black Zombie creature token.
{b}, Sacrifice a creature you control: Binder of Cruel Life gets +1/+1 until the end of turn.
"And you thought these violent delights would end at death."