The Sixth Doctor, Romana II, and Jace, Ingenious Mind-Mage

Prerequisites

• The Sixth Doctor on the battlefield
• Romana II on the battlefield
• Jace, Ingenious Mind-Mage on the battlefield
• undefined available

Steps

1. Cast Jace by paying
2. The Sixth Doctor triggers, copying the Jace spell, with the copy being nonlegendary
3. Resolve both Jace spells
4. Activate a mana-producing creature by tapping it, adding at least
5. Activate Romana II by paying and tapping it, creating a copy of the Jace token
6. Activate a Jace token's second loyalty ability by putting a loyalty counter on it, untapping all creatures you control
7. Repeat from step 4

Results

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