Basalt Monolith + Agatha of the Vile Cauldron + March of the Machines

Basalt Monolith

Agatha of the Vile Cauldron

March of the Machines

How it works

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

By bringing March of the Machines to the battlefield, Basalt Monolith is transformed into an artifact creature with a mana value of three, turning it into a legal target for Agatha of the Vile Cauldron. With Agatha's power pumping a three-mana reduction into the mix, the cost to untap Basalt Monolith drops from three mana down to a single mana. Since tapping the Monolith yields three colorless mana while untapping it now only costs one, you are left with a net gain of two mana with every cycle, fueling infinite colorless mana for your spells and abilities.