Zovaal, The Jailer

When Zovaal, The Jailer enters the battlefield split your library into two piles, then exile one of them. Put all
cards exiled this way into your graveyard. Then shuffle your library.

Descend 20 - If there are twenty or more permanents in your graveyard Zovaal, The Jailer is indestructible.
As long as Zovaal, The Jailer is on the battlefield under your control, you may play cards from your graveyard as
if they had flash. They cost life equal to the cards converted mana cost.

All