Worker in the Walls

Haste
Worker in the Walls has protection from {u}{b}{r}{g}. When Worker in the Walls leaves the battlefield, put it into your library and shuffle it.
{t}{b}{r}: Sacrifice two human creatures. Search your library for a card named Gatekeeper, Great Demon Master and put it onto the battlefield.
{t}{3}{b}{r}: Sacrifice Worker in the Walls. Create ten 1/1 Dark Broodling creature tokens. Cast this ability any time you could cast an instant.