Basalt Monolith + Myr Welder + Heartstone

Basalt Monolith

Myr Welder

Heartstone

How it works

1. Activate Myr Welder using Basalt Monolith's first ability by tapping it, adding CCC.
2. Activate Myr Welder using Basalt Monolith's second ability by paying 2, untapping it.
3. Repeat.

This clever loop turns Myr Welder into a self-sustaining mana engine by having it imprint Basalt Monolith, granting the creature the ability to tap for three colorless mana. Normally, untapping the Monolith would cost three mana, but Heartstone steps in to reduce that activation cost to just two, leaving you with a net gain of one colorless mana each time you cycle through the process. Because Myr Welder copies the exact activated abilities without inheriting Basalt Monolith's drawback of failing to untap during your untap step, you can repeat this tap-and-untap sequence indefinitely to generate infinite colorless mana.