Activate Cinderhaze Wretch's second ability by putting a -1/-1 counter on it, untapping it.
Repeat step 1 until Cinderhaze Wretch dies as a state-based action due to having zero or less toughness.
Myrkul triggers, causing you to exile Cinderhaze Wretch and create a token copy of Cinderhaze Wretch that is an enchantment and loses all other card types.
Activate the Cinderhaze Wretch token by tapping it, adding ({G} magic symbol) .
Activate the Cinderhaze Wretch token's second ability by putting a -1/-1 counter on it, untapping it.