Voltaic Construct, Mana Vault, and Xenic Poltergeist

Prerequisites

• Voltaic Construct on the battlefield
• Mana Vault on the battlefield
• Xenic Poltergeist on the battlefield
• Xenic Poltergeist does not have summoning sickness
• Mana Vault does not have summoning sickness

Steps

1. Activate Xenic Poltergeist by tapping it, causing Mana Vault to become an artifact creature until your next upkeep
2. Activate Mana Vault by tapping it, adding
3. Activate Voltaic Construct by paying , untapping Mana Vault
4. Repeat from step 2

Results

• Infinite colorless mana