Cacophony Unleashed (CMM) from Commander Masters, available at 401 Games Canada.

• Rarity: Rare
• Finish: Normal
• Artist: Deruchenko Alexander
• Card Text:
  When Cacophony Unleashed enters the battlefield, if you cast it, destroy all nonenchantment creatures.
  Whenever Cacophony Unleashed or another enchantment enters the battlefield under your control, until end of turn, Cacophony Unleashed becomes a legendary 6/6 Nightmare God creature with menace and deathtouch. It's still an enchantment.