Purgatory

Whenever a nontoken creature card is put into your graveyard from the battlefield, exile that card.
At the beginning of your upkeep, you may pay {4} and 2 life. If you do, return a card exiled with Purgatory to the battlefield.
"Those that seek penance enter the void, so that they may serve and die again before their final judgement. The others do not have a choice." ~ Teysa