Ertha Jo, Frontier Mentor, Metalworker, and Voltaic Key

Prerequisites

• Ertha Jo, Frontier Mentor on the battlefield
• Metalworker on the battlefield
• Voltaic Key on the battlefield

Steps

1. Activate Metalworker by tapping it, revealing at least one artifact card from your hand and adding at least
2. Activate Voltaic Key by paying and tapping it, targeting Metalworker
3. Ertha Jo's second ability triggers, copying Voltaic Key's ability, targeting Voltaic Key
4. Resolve both Voltaic Key abilities, untapping it and Metalworker
5. Repeat

Results

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