Cacophony Unleashed is a rare Enchantment card from Commander Masters (CMM), collector number 761. Current market price: $0.99 (foil $2.88), TCGplayer market prices via Scryfall.
When this enchantment enters, if you cast it, destroy all nonenchantment creatures. Whenever this enchantment or another enchantment you control enters, until end of turn, this enchantment becomes a legendary 6/6 Nightmare God creature with menace and deathtouch. It's still an enchantment.