Monk Gyatso, Priest of Urabrask, and Umbral Mantle

Prerequisites

• Monk Gyatso on the battlefield
• Priest of Urabrask on the battlefield
• Umbral Mantle on the battlefield

Steps

1. Activate Umbral Mantle's equip ability by paying , targeting Priest of Urabrask
2. Monk Gyatso triggers, airbending Priest of Urabrask
3. The Umbral Mantle ability fizzles due to no longer having a legal target
4. Cast Priest of Urabrask from exile by paying
5. When Priest of Urabrask enters, it triggers, adding
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite storm count
• Infinite red mana
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinitely large creature until end of turn