The Book of Vile Darknesss

Attach to creature.Sacrifice three creatures with power 3 or less.If you do all black creatures/artifact creatures get a +3/+3 counter.This artifact has toughness equal to
the creature it is attached to but it has no
power.If The Book of Vile Darkness dies return
it to your hand.If all dark creatures die put
this card in your graveyard.