Voltaic Construct + Mycosynth Lattice + Rainveil Rejuvenator

Voltaic Construct

Mycosynth Lattice

Rainveil Rejuvenator

How it works

1. Activate Rainveil Rejuvenator by tapping it, adding at least .
2. Activate Voltaic Construct by paying 2, untapping Rainveil Rejuvenator.
3. Repeat

By transforming every permanent on the battlefield into an artifact courtesy of Mycosynth Lattice, the grand alchemical stage is set for Voltaic Construct to target essentially anything you control. When you direct that untap ability toward Rainveil Rejuvenator, its tap-to-add-green-mana ability is refreshed as long as its power is at least 3, easily covering the activation cost while spinning out an infinite surplus of colored mana.