Tawnos, Urza's Apprentice, and Sands of Time

Prerequisites

• Tawnos, Urza's Apprentice on the battlefield
• Sands of Time on the battlefield
• All other permanents must be able to produce at least
• Tawnos does not have summoning sickness

Steps

1. At the beginning of the upkeep step, Sands of Time triggers
2. In response, tap all of your mana producing permanents
3. Activate Tawnos, copying the Sands of Time trigger
4. Let the copy resolve, untapping all your creatures, lands, and artifacts
5. Repeat from step 2

Results

• Infinite Mana during the upkeep step
• Infinite taps
• Infinite untap