Demon of Annihilation

When Demon of Annihilation enters play, target player searches his or her library for four cards,
exiles the rest of their library and puts these four
cards on top of their library in a random order.
That player cannot lose the game due to running
out of cards in their library.
When Demon of Annihilation leaves play, return
all exiled cards back to target player's library.
That player shuffles their library.