Priority Boarding is a uncommon Enchantment card from Unfinity (UNF), collector number 119. Current market price: $0.15 (foil $0.38), TCGplayer market prices via Scryfall.
Whenever you roll a die, you may reveal the top card of your library. Do this only once each turn. Whenever you reveal a card with mana value less than the result this way, you may exile it. If you do, you may play it this turn.