Voltaic Construct + Empowered Autogenerator + Karn, the Great Creator

Voltaic Construct

Empowered Autogenerator

Karn, the Great Creator

How it works

1. Animate Empowered Autogenerator using Karn, the Great Creator.
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.