Descent into Avernus is a rare Enchantment card from Battle for Baldur's Gate Promos (PCLB), collector number 169s. Current market price: — (foil $19.14), TCGplayer market prices via Scryfall.
At the beginning of your upkeep, put two descent counters on this enchantment. Then each player creates X Treasure tokens and this enchantment deals X damage to each player, where X is the number of descent counters on this enchantment.