Lithoform Engine, Tezzeret the Seeker, and Mana Vault

Prerequisites

• Lithoform Engine on the battlefield
• Tezzeret the Seeker on the battlefield
• Mana Vault on the battlefield

Steps

1. Activate Tezzeret the Seeker's first ability by putting a loyalty counter on it
2. Holding priority, activate Mana Vault by tapping it, adding
3. Activate Lithoform Engine's first ability by paying and tapping it, copying Tezzeret the Seeker's ability, targeting Lithoform Engine and Mana Vault
4. Resolve the copy of Tezzeret the Seeker's ability, untapping Mana Vault and Lithoform Engine
5. Repeat from step 2

Results

• Infinite mana artifacts you control can produce
• Infinite untap of artifacts you control