Eidolon of Penitence

Whenever Eidolon of Penitence attacks, creatures
your opponents control get -X/-X until end of
turn, where X is the number of creature cards in
that player's graveyard.
Bestow {1}{b}{b}
Enchanted creature gains "This creature can't be sacrificed." and "Whenever enchanted creature attacks, each opponent loses X life, where X is the number of creature cards in that player's
graveyard."