Voltaic Construct + Ashnod's Transmogrant + Vhal, Candlekeep Researcher

Voltaic Construct

Ashnod's Transmogrant

Vhal, Candlekeep Researcher

How it works

1. Cause Vhal to become an artifact using Ashnod's Transmogrant.
2. Activate Vhal by tapping it, adding at least CCC.
3. Activate Voltaic Construct by paying 2, untapping Vhal.
4. Repeat from step 2.

To pull off this brilliant transmutation, we first rely on Ashnod's Transmogrant to permanently turn Vhal, Candlekeep Researcher into an artifact creature, setting the stage for everything else. Once Vhal wears this new mechanical mantle, her tap ability generates a surplus of colorless mana fueled by her toughness. We then channel two of that mana into Voltaic Construct to untap Vhal, letting us loop the process indefinitely. The result is an engine that churns out infinite colorless mana (though you'll need to find another outlet for it since it can't be spent from your hand) and infinitely untaps your artifact creatures.