Unstable Necromancy

At the beginning of your upkeep exile a card
from your graveyard.
At the beginning of your upkeep target creature
in your graveyard gains unearth. Its unearth cost
is equal to its manacost.
(Cost: Return this card from your graveyard to
the battlefield. It gains haste. Exile it at the beginning
of the next end step or if it would leave the battlefield.
Unearth only as a sorcery.)