Howling Wraiths

Cacophony Unleashed
When Howling Wraiths enters, if you cast it, destroy all nonenchantment creatures.

Whenever Howling Wraiths or another enchantment you control enters, until end of turn, Howling Wraiths becomes a legendary 6/6 Nightmare God creature with menace and deathtouch. It's still an enchantment.