Gibbering Descent is a rare Enchantment card from Future Sight (FUT), collector number 66. Current market price: $2.74 (foil $7.08), TCGplayer market prices via Scryfall.
At the beginning of each player's upkeep, that player loses 1 life and discards a card. Hellbent — Skip your upkeep step if you have no cards in hand. Madness {2}{B}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)