Rings of Brighthearth + Basalt Monolith

Rings of Brighthearth
Basalt Monolith

Requires
All permanents on the battlefield. 2 available.
Steps
  1. Activate Basalt Monolith's first ability by tapping it, adding ccc
  2. Activate Basalt Monolith's last ability by paying 3
  3. Rings of Brighthearth triggers, causing you to pay 2 to copy Basalt Monolith's last ability
  4. Resolve the copy of Basalt Monolith's last ability, untapping it
  5. Activate Basalt Monolith's first ability by tapping it, adding ccc
  6. Resolve the Basalt Monolith ability from step 2, untapping it
  7. Repeat
Results
Infinite colorless mana.