Voltaic Construct + Biotransference + Axebane Guardian

Voltaic Construct

Biotransference

Axebane Guardian

How it works

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

This clever loop turns Axebane Guardian into an unlimited mana source by rewriting the battlefield's rules with Biotransference. Because Biotransference makes all your creatures into artifacts, Axebane Guardian qualifies as an artifact creature, allowing Voltaic Construct to target and untap it for the cost of {2}. As long as Axebane Guardian's ability taps for at least three mana, you can infinitely cycle through its mana generation and the Construct's untap ability to yield an endless supply of colored mana and untaps for your entire artifact creature army.