Voltaic Construct + Biotransference + Bighorner Rancher

Voltaic Construct

Biotransference

Bighorner Rancher

How it works

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

This clever loop turns your creatures into a self-sustaining mana engine by leaning on Biotransference, which makes Biotransference's artifact type-granting passive ability apply to Bighorner Rancher and turn the cowhand into an artifact creature. Because Bighorner Rancher is now an artifact creature, it becomes a legal target for Voltaic Construct's untap ability. As long as the greatest power among your creatures is 3 or greater, tapping Bighorner Rancher produces more than enough green mana to pay for Voltaic Construct's activation fee, leaving you with an infinite supply of green mana and infinite untaps.