Cacophony Unleashed

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.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6ogwhec45dpb1hx79gwlq6.