Voltaic Construct + Liquimetal Torque + Overgrown Battlement

Voltaic Construct

Liquimetal Torque

Overgrown Battlement

How it works

1. Cause Overgrown Battlement to become an artifact using Liquimetal Torque.
2. Activate Overgrown Battlement by tapping it, adding at least .
3. Activate Voltaic Construct by paying 2, untapping Overgrown Battlement.
4. Repeat from step 2.

This clever loop starts with Liquimetal Torque transforming Overgrown Battlement into an artifact, which is crucial because it makes the defender eligible to be targeted by Voltaic Construct. Once the Battlement is an artifact, tapping it yields a bounty of green mana scaled by its own defender keyword. You then funnel a portion of that green mana into Voltaic Construct's activation cost to untap the Battlement, leaving you with an endless surplus of mana.