Ugin, the Ineffable, Cloud Key, and Primordial Mist

Prerequisites

• Ugin, the Ineffable on the battlefield
• Cloud Key on the battlefield
• Primordial Mist on the battlefield
• You have a creature card in hand that has Morph or Megamorph
• "Creature" chosen with Cloud Key

Steps

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

Results

• Infinite ETB
• Infinite LTB
• Infinite storm count