Voltaic Construct + Astral Cornucopia + Tezzeret, Betrayer of Flesh

Voltaic Construct

Astral Cornucopia

Tezzeret, Betrayer of Flesh

How it works

1. Animate Astral Cornucopia using Tezzeret, Betrayer of Flesh.
2. Activate Astral Cornucopia by tapping it, adding at least three mana of any color
3. Activate Voltaic Construct by paying 2, untapping Astral Cornucopia.
4. Repeat from step 2.

This loop relies on transforming your mana producer into a creature so that you can continuously untap and reuse it for a net gain. By using Tezzeret, Betrayer of Flesh's minus-two ability, Astral Cornucopia becomes an artifact creature, allowing Voltaic Construct to target it with its untap ability. Normally, activating the Construct would cost two mana, but Tezzeret's passive ability reduces the first artifact activation cost each turn by two, removing the mana restriction entirely when you have at least three charge counters on the Cornucopia. Tapping the Cornucopia for three or more mana and paying two to untap it with the Construct leaves you with a growing surplus of infinite colored mana and infinite untaps.