Voltaic Construct + Heronblade Elite + Thran Forge

Voltaic Construct

Heronblade Elite

Thran Forge

How it works

1. Cause Heronblade Elite to become an artifact using Thran Forge.
2. Activate Heronblade Elite by tapping it, adding at least 3.
3. Activate Voltaic Construct by paying 2, untapping Heronblade Elite.
4. Repeat from step 2.

To pull off this infinite mana engine, we first use Thran Forge to turn Heronblade Elite into an artifact in addition to its other types, ensuring it becomes a valid target for our untap effects. Once the Elite is an artifact and possesses enough power to produce more than the cost to untap it, we tap it for a hefty sum of mana. We then pump a portion of those profits into Voltaic Construct's ability, untapping the Heronblade Elite so it's ready to tap and repeat the cycle endlessly.