Abyssal Dragon

Delve (Each card you exile from your graveyard
while casting this spell pays for {1}.)
Flying, menace
Creature cards in your graveyard have unearth.
The unearth cost is equal to the card's mana cost. (Pay the card's mana cost: Return it to the battlefield. The creature gains haste. Exile it at the beginning of the
next end step or if it would leave the battlefield.
Unearth only as a sorcery.)