Forsaken Oni

Painborn (Each 1 life you pay while casting this
pays for {1}. It enters the battlefield with a -1/-1 counter on it for each 1 life paid this way.)
When Forsaken Oni enters the battlefield, discard a number of cards equal to its power.
When Forsaken Oni dies, if you are its
owner, you may return it to the battlefield
under an opponent's control.