Tathamet, The Prime Evil

When Tathamet enters the battlefield, sacrifice it
unless it escaped.

Whenever Tathamet enters the battlefield or attacks, search your library for a Legendary Demon creature
card, put it into your hand, then shuffle.

Escape — {w}{u}{b}{r}{g}, Exile a Legendary Demon Creature card from your graveyard. (You may cast
this card from your graveyard for its escape cost)