Voltaic Construct + Prismatic Geoscope + Tezzeret, Betrayer of Flesh

Voltaic Construct

Prismatic Geoscope

Tezzeret, Betrayer of Flesh

How it works

1. Animate Prismatic Geoscope using Tezzeret, Betrayer of Flesh.
2. Activate Prismatic Geoscope by tapping it, adding at least three mana of any color
3. Activate Voltaic Construct by paying 2, untapping Prismatic Geoscope.
4. Repeat from step 2.

To pull off this infinite mana engine, you first need to use Tezzeret, Betrayer of Flesh’s second ability to turn Prismatic Geoscope into an artifact creature with base power and toughness 4/4. Because Tezzeret's passive ability reduces the first activated ability of an artifact you activate each turn by {2}, activating Voltaic Construct's untap ability becomes completely free. This creates a closed loop where you tap the animated Prismatic Geoscope for a bounty of colored mana—assuming you control enough basic land types to make it yield at least three mana—and then use the free untap from Voltaic Construct to ready it for another rotation.