Hidden Grave

Whenever a creature you control dies, you may
instead exile it with 3 Mummify counters on it.
At the beginning of your upkeep, remove one of
those counters. If a creature exiled with this
effect would leave exile, remove all counters
from it.
{2}{w}{b}{g}: Return target creature in exile with
a mummify counter on it to the battlefield under
your control. Activate this ability only any time
you could play a sorcery.