All-Seeing Arbiter [Streets of New Capenna]

Set: Streets of New Capenna Type: Creature — Avatar Rarity: Mythic Cost: {4}{U}{U} FlyingWhenever All-Seeing Arbiter enters the battlefield or attacks, draw two cards, then discard a card.Whenever you discard a card, target creature an opponent controls gets -X/-0 until your next turn, where X is the number of different mana values among cards in your graveyard.