Voltaic Construct + Empowered Autogenerator + Xenic Poltergeist

Voltaic Construct

Empowered Autogenerator

Xenic Poltergeist

How it works

1. Animate Empowered Autogenerator using Xenic Poltergeist.
2. Activate Empowered Autogenerator by tapping it, putting a charge counter on it and adding 1 for each charge counter on it.
3. Activate Voltaic Construct by paying 2, untapping Empowered Autogenerator.
4. Repeat from step 2.

This clever loop transforms a humble mana rock into a self-sustaining engine by relying on Xenic Poltergeist to animate Empowered Autogenerator into an artifact creature, setting its power and toughness to its mana value. Once it can be targeted as a creature, Voltaic Construct steps in to untap it for a modest fee of two mana. Because Empowered Autogenerator scales its mana production exponentially with each charge counter it accumulates, the mana generated quickly outpaces the cost of the untap ability, leaving you with an endless surplus of colored mana and total mastery over your artifact creatures.