Diablo, Lord of Terror

While Diablo, Lord of Terror is on the field all Non-Legendary Creatures opponents control lose -3/-1.
{4}{t}: Target Player reveals their hand. You and that Player both choose a card, that Player keeps those two cards the rest are Discarded. Deal damage to that player equal casting cost of the Discarded cards.
"Terror comes in many forms. A child. A warrior. Even...a friend."