Quest for the Nihil Stone is a rare Enchantment card from The List (PLST), collector number WWK-64. Current market price: $8.69, TCGplayer market prices via Scryfall.
Whenever an opponent discards a card, you may put a quest counter on this enchantment. At the beginning of each opponent's upkeep, if that player has no cards in hand and this enchantment has two or more quest counters on it, you may have that player lose 5 life.