Psychic Allergy is a rare Enchantment card from The Dark (DRK), collector number 34. Current market price: $3.12, TCGplayer market prices via Scryfall.
As this enchantment enters, choose a color. At the beginning of each opponent's upkeep, this enchantment deals X damage to that player, where X is the number of nontoken permanents of the chosen color they control. At the beginning of your upkeep, destroy this enchantment unless you sacrifice two Islands.