Rings of Brighthearth, Seeker of Skybreak, and Llanowar Tribe

Prerequisites

• Rings of Brighthearth on the battlefield
• Seeker of Skybreak on the battlefield
• Llanowar Tribe on the battlefield
• Llanowar Tribe and Seeker of Skybreak do not have summoning sickness

Steps

1. Activate Llanowar Tribe by tapping it, adding
2. Activate Seeker of Skybreak by tapping it
3. Rings of Brighthearth triggers, allowing you to pay to copy Seeker of Skybreak's ability and choose a new target for the copy
4. Resolve both copies of Seeker of Skybreak's ability, untapping Seeker of Skybreak and Llanowar Tribe
5. Repeat
6. Once you have infinite mana, you may untap any creature instead of Llanowar Tribe in step 4

Results

• Infinite green mana
• Infinite untap of creatures