Miirym, Sentinel Wyrm, Cloudstone Curio, and Dracogenesis

Prerequisites

• Miirym, Sentinel Wyrm on the battlefield
• Cloudstone Curio on the battlefield
• Dracogenesis on the battlefield
• undefined

Steps

1. Cast the Dragon in your hand without paying its mana cost
2. When the Dragon enters the battlefield, Cloudstone Curio triggers if the Dragon isn't an artifact and Miirym triggers
3. Resolve the Cloudstone Curio trigger, if applicable, choosing to return nothing
4. Resolve the Miirym trigger, creating a token copy of the Dragon that isn't legendary if the Dragon was legendary
5. When the Dragon token enters the battlefield, Cloudstone Curio triggers, returning the Dragon cast in step 1 from the battlefield to your hand
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite storm count
• Infinite creature tokens
• Infinite copies of all nontoken Dragons you control except Miirym