Crowded Crypt
{2}{B}Artifact
{T}: Add {B}. Whenever a creature you control dies, put a corpse counter on this artifact. {4}{B}{B}, {T}, Sacrifice this artifact: Create a 2/2 black Zombie creature token with decayed for each corpse counter on this artifact. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.)