Cast the creature using its morph or megamorph cost by paying {0}, putting it face-down on the battlefield as a 3/3 creature.
Activate Primordial Mist by exiling the face down creature face up, allowing you to cast it this turn.
Repeat.

Infinite ETB

Infinite LTB

Infinite storm count

Ugin, the Ineffable

Dream Chisel

Primordial Mist

Cast the creature card in your hand for its morph or megamorph cost by paying {0}, putting it onto the battlefield face down as a 2/2 creature.
When the creature enters the battlefield, Cloudstone Curio triggers, returning another creature card with morph or megamorph from the battlefield to your hand.
Repeat.

Cloudstone Curio

Cast the creature with morph or megamorph for its morph or megamorph cost by paying {0}, putting it on the battlefield face-down as a 2/2 creature.
Activate Primordial Mist by exiling the face-down creature face-up, allowing you to cast it from exile this turn.
Repeat.

Combos with "Dream Chisel"