Voltaic Construct + Incubation Druid + Neurok Transmuter

Voltaic Construct

Incubation Druid

Neurok Transmuter

How it works

1. Cause Incubation Druid to become an artifact using Neurok Transmuter.
2. Activate Incubation Druid by tapping it, adding three mana of any type a land you control can produce
3. Activate Voltaic Construct by paying 2, untapping Incubation Druid.
4. Repeat from step 2.

This clever machinery starts with Neurok Transmuter, whose first ability permanently transforms Incubation Druid into an artifact creature for the turn, making it a legal target for Voltaic Construct. Once the Druid is juiced up with a +1/+1 counter so its tap ability yields three mana, you can feed just two of that mana back into Voltaic Construct to untap it, netting a profit of one mana each cycle. You repeat this loop to generate infinite mana of any type your lands can produce, leaving your artifact creatures fully untaped and ready to power whatever devastation you dream up next.