Cranium Rat Swarm

Whenever Cranium Rat Swarm is put into a
graveyard from the battlefield, each opponent
must exile the top card of their library.
Unearth {3}{b}{b} ({3}{b}{b}: Return this card from
your graveyard to the battlefield. It gains haste.
Exile it at the beginning of the next end step or
if it would leave the battlefield. Unearth only
as a sorcery.)