He who is Trapped in the Dark

When He who is Trapped in the Dark enters the battlefield, search any player's library for a
creature card, reveal it and exile it. Then shuffle.
Gaze into the abyss.
When He who is Trapped in the Dark leaves the battlefield, return the exile card to its owner's battlefield.
"The traitor does not deserve a name to be remembered
by. But in the abyss he would be given another name."