Ostia, Herald of War

{t}: Each player searches their library for three creatures, then exiles them face down. At the beginning of next combat, choose one of the cards exiled this way for each opponent, then an opponent of your choice chooses one of your cards you exiled this way. Each player plays their chosen card without paying their mana cost. If the creature you played this way has the lowest converted mana cost, deal 5 damage to each of the creatures opponents played this way.