Zirda, the Dawnwaker, and Basalt Monolith

Prerequisites

• Zirda, the Dawnwaker on the battlefield
• Basalt Monolith on the battlefield

Steps

1. Activate Basalt Monolith's first ability by tapping it, adding
2. Activate Basalt Monolith's last ability by paying , untapping it
3. Repeat

Results

• Infinite colorless mana