Idris, Soul of the TARDIS, Basalt Monolith, and Agatha of the Vile Cauldron

Prerequisites

• Idris, Soul of the TARDIS on the battlefield
• Basalt Monolith in exile
• Agatha of the Vile Cauldron on the battlefield
• Idris does not have summoning sickness
• Agatha of the Vile Cauldron has power 1 or greater

Steps

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

Results

• Infinite colorless mana