Maddening Imp is a rare Creature — Imp card from Tempest (TMP), collector number 143. Current market price: $1.24, TCGplayer market prices via Scryfall.
Flying {T}: Non-Wall creatures the active player controls attack this turn if able. At the beginning of the next end step, destroy each of those creatures that didn't attack this turn. Activate only during an opponent's turn and only before combat.