X, Eldritch Void

Shroud, Menace

Creatures you control cannot be exiled by opponents or affected by Deathtouch.

Whenever X enters the battlefield or attacks, you may pay {x} mana, if you do so look through your deck or graveyard and play a card equal to or less than the mana you paid. If played from your graveyard, it gains haste and attacks alongside X but you exile it at your end step.