Voltaic Construct + Ashnod's Transmogrant + Rainveil Rejuvenator

Voltaic Construct

Ashnod's Transmogrant

Rainveil Rejuvenator

How it works

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

To set this engine in motion, you first need to use Ashnod's Transmogrant to permanently transform Rainveil Rejuvenator into an artifact creature, turning it into a valid target for Voltaic Construct. Once that foundation is laid, Rainveil Rejuvenator can tap for a surplus of green mana thanks to its power scaling. You then funnel a portion of that green mana back into Voltaic Construct's ability to untap the Rejuvenator, leaving you with a net gain of mana each time you cycle through the loop.