Psychic Allergy

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.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6oqqndjre7pb1hl9vd8zwy.