Cramped Bunker is a rare Enchantment card from Unstable (UST), collector number 129. Current market price: $0.14 (foil $0.43), TCGplayer market prices via Scryfall.
At the beginning of each opponent's upkeep, that player moves a permanent they control to touch this enchantment and no other permanents. If the player can't, destroy each permanent they control that isn't touching this enchantment, then sacrifice it.