Bone Harvester

Sacrifice 3 skeletons you control: put Bone Harvester onto the battlefield.
Eminence - Skeleton creatures you cast have "Offspring 1, then put a bone counter on a creature you don't control at random. "
At the start of each turn, choose a creature
with a bone counter on it. Up to X skeletons
you control get +X/+X until end of turn, where X is the creature's power, and gains up to one ability from that creature.