Bone Herder

Relapse (When this card is put into your graveyard
from anywhere, shuffle a random card from your graveyard into your library.)
Creatures you control with relapse get +1/+0.
Whenever another creature card leaves a player's graveyard, if Bone Herder is in your graveyard,
you may pay {b}. If you do, create a 1/1 black
Skeleton Warrior creature token with relapse.