Devoid (This card has no color.)
When Catacomb Sifter enters the battlefield, put a 1/1 colorless Eldrazi Scion creature token onto the battlefield. It has "Sacrifice this creature: Add 1 to your mana pool."
Whenever another creature you control dies, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)