Voltaic Construct + Astral Cornucopia + Toymaker

Voltaic Construct

Astral Cornucopia

Toymaker

How it works

1. Animate Astral Cornucopia using Toymaker.
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 clever three-piece engine transforms a humble mana rock into a self-sustaining powerhouse. By using Toymaker to temporarily turn Astral Cornucopia into an artifact creature, you enable it to be repeatedly untapable by Voltaic Construct's ability. As long as Astral Cornucopia enters with at least three charge counters, tapping it for mana generates a surplus that easily pays for both the construct's activation and the mana needed to keep the loop going, netting you infinite colored mana and infinite untaps.