Basalt Monolith + Heartstone + Sydri, Galvanic Genius

Basalt Monolith

Heartstone

Sydri, Galvanic Genius

How it works

1. Activate Sydri's first ability by paying , making Basalt Monolith a 3/3 artifact creature until end of turn.
2. Activate Basalt Monolith's first ability by tapping it, adding CCC.
3. Activate Basalt Monolith's last ability by paying 2, untapping it.
4. Repeat.

By animating Basalt Monolith into a 3/3 artifact creature using Sydri, Galvanic Genius, we clever alchemists bypass its normal stubbornness and drop its untap cost to just two generic mana thanks to Heartstone's cost-reducing presence. Tapping the Monolith yields three colorless mana, but spending two of that to untap it leaves a net surplus of one colorless mana each time you cycle through the loop. You can repeat this wondrous transmutation as many times as you desire, converting simple mechanical engineering into an infinite supply of colorless mana.