Father Ariandel and Friede

At the beginning of combat on your turn, you
may discard a card. If you do, target creature you control gets +X/+X and menace until end of
turn, where X is the discarded card's converted
mana cost.
Whenever one or more cards are put into your graveyard from anywhere, if you have ta least 15
cards in your graveyard, exile Father Ariandel
and Friede, then return them to the battlefield transfromed under their owner's control.