That say “ When it enters exile target creature an opponent controls until this creature leaves the battlefield.” but it doesn't work like this, my card simply remains exiled this way. I used to block him during the combat; he died and went to the graveyard (I'm pretty sure it is considered leaving the battlefield) I sacrificed my creatures to return the card exiled back to the battlefield but never happened. I had "Mighty Mutanimals" on the battlefield, he played "henchbots" exiling my creature, 2 turns later i used to block his henchbots that died (leaving the battlefield) but my creature never came back and i lost the game.