Ertha Jo, Frontier Mentor, Palladium Myr, and Voltaic Key

Prerequisites

• Ertha Jo, Frontier Mentor on the battlefield
• Palladium Myr on the battlefield
• Voltaic Key on the battlefield

Steps

1. Activate Palladium Myr by tapping it, adding
2. Activate Voltaic Key by paying and tapping it, targeting Palladium Myr
3. Ertha Jo's second ability triggers, copying Voltaic Key's ability, targeting Voltaic Key
4. Resolve both Voltaic Key abilities, untapping it and Palladium Myr
5. Repeat

Results

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