Voltaic Construct + Grim Monolith + March of the Machines

Voltaic Construct

Grim Monolith

March of the Machines

How it works

1. Activate Grim Monolith by tapping it, adding CCC.
2. Activate Voltaic Construct by paying 2, untapping Grim Monolith.
3. Repeat.

By turning noncreature artifacts into artifact creatures, March of the Machines lays the critical foundation that allows Voltaic Construct to target them as artifact creatures. This lets the Construct repeatedly untap Grim Monolith for just two generic mana, bypassing the Monolith's natural refusal to untap during your untap step. Because tapping the Monolith yields three colorless mana while the untap ability costs only two, this loop continuously generates a surplus of mana.