Lithoform Engine, and Teferi, Temporal Archmage

Prerequisites

• Lithoform Engine on the battlefield
• Teferi, Temporal Archmage on the battlefield
• You control at least three lands

Steps

1. Activate Teferi, Temporal Archmage's second ability by removing a loyalty counter from it
2. In resopnse, activate Lithoform Engine's first ability by paying and tapping it, copying Teferi's activated ability
3. Let the copied ability resolve, untapping three lands and Lithoform Engine
4. Activate those lands by tapping them, adding at least
5. Repeat from step 2
6. Once you have infinite mana, you may untap any permanents in step 3

Results

• Infinite mana lands you control can produce
• Infinite untap of permanents