Priest of Titania, Rings of Brighthearth, and Tidewater Minion

Prerequisites

• Priest of Titania on the battlefield
• Rings of Brighthearth on the battlefield
• Tidewater Minion on the battlefield
• Priest of Titania and Tidewater Minion do not have summoning sickness
• There are at least three Elves on the battlefield

Steps

1. Activate Priest of Titania by tapping it, adding at least
2. Activate Tidewater Minion's second ability by tapping it, targeting itself
3. Rings of Brighthearth triggers, causing you to pay to copy Tidewater Minion's ability, targeting Priest of Titania
4. Resolve both Tidewater Minion abilities, untapping it and Priest of Titania
5. Repeat

Results

• Infinite green mana
• Infinite mana creatures you control can produce
• Infinite untap of creatures you control