Basalt Monolith + Forsaken Monument

Basalt Monolith
Forsaken Monument

Requires
All permanents on the battlefield.
Steps
  1. Activate Basalt Monolith's first ability by tapping it, adding cccc
  2. Activate Basalt Monolith's last ability by paying 3, untapping it
  3. Repeat
Results
Infinite colorless mana.