Basalt Monolith, Myr Welder, and Agatha of the Vile Cauldron

Prerequisites

• Basalt Monolith in exile
• Myr Welder on the battlefield
• Agatha of the Vile Cauldron on the battlefield

Steps

1. Activate Myr Welder using Basalt Monolith's first ability by tapping it, adding
2. Activate Myr Welder using Basalt Monolith's second ability by paying at most , untapping it
3. Repeat

Results

• Infinite colorless mana