Filigree Sages + Prototype Portal + Mistvault Bridge + Tiller Engine + Zirda, the Dawnwaker

Filigree Sages

Prototype Portal

Mistvault Bridge

Tiller Engine

Zirda, the Dawnwaker

How it works

1. Activate Prototype Portal by paying 0 and tapping it, creating a token copy of Mistvault Bridge.
2. When Mistvault Bridge enters the battlefield, Tiller Engine triggers, untapping it.
3. Activate the Mistvault Bridge token by tapping it, adding .
4. Activate Filigree Sages by paying , untapping Prototype Portal.
5. Repeat.

This brilliant engine exploits cost reduction to generate an endless supply of artifact lands and landfall triggers for zero net mana. By designating Zirda, the Dawnwaker as your companion, you shrink the activation cost of Prototype Portal down to just {0}, letting you churn out a copy of Mistvault Bridge whenever you need one. Because Mistvault Bridge enters the battlefield tapped, Tiller Engine triggers immediately to untap it, allowing the land to tap for {U}. You then feed that blue mana directly into Filigree Sages to untap Prototype Portal, looping the entire process as many times as you desire.