Gogo, Mysterious Mime, and Ioreth of the Healing House

Prerequisites

• Gogo, Mysterious Mime on the battlefield
• Ioreth of the Healing House on the battlefield

Steps

1. At the beginning of your combat phase, Gogo triggers, causing it to become a copy of Ioreth until end of turn, and giving Gogo and Ioreth haste until end of turn
2. Activate Gogo's second ability by tapping it, untapping Ioreth and another legendary creature
3. Activate Ioreth's second ability by tapping it, untapping Gogo and another legendary creature
4. Repeat from step 2

Results

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