Ertha Jo, Frontier Mentor, and Seeker of Skybreak

Prerequisites

• Ertha Jo, Frontier Mentor on the battlefield
• Seeker of Skybreak on the battlefield
• Seeker of Skybreak does not have summoning sickness

Steps

1. Activate Seeker of Skybreak by tapping it, targeting itself
2. Ertha Jo's second ability triggers, copying Seeker of Skybreak's ability, targeting any other creature
3. Resolve both Seeker of Skybreak abilities, untapping it and the other targeted creature
4. Repeat

Results

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