The Cyber-Controller + Urza, Lord High Artificer + Krark-Clan Ironworks + Mycosynth Golem + Mycosynth Lattice

The Cyber-Controller

Urza, Lord High Artificer

Krark-Clan Ironworks

Mycosynth Golem

Mycosynth Lattice

How it works

1. Activate Urza's first ability three times by tapping three artifacts you control, adding 3.
2. Cast The Cyber-Controller from the command zone, choosing for X to equal the amount of artifacts you control minus twice the number of times The Cyber-Controller has been cast from the command zone this game, but paying a total of 3 due to Mycosynth Lattice and Mycosynth Golem.
3. When The Cyber-Controller enters the battlefield, it triggers, causing each opponent to mill X cards, and then putting all creature cards milled this way onto the battlefield face down under your control as 2/2 Cyberman artifact creatures.
4. Activate Urza's first ability by tapping The Cyber-Controller, adding 1.
5. Activate Krark-Clan Ironworks by sacrificing The Cyber-Controller, adding CC.
6. Choose to return The Cyber-Controller to the command zone from your graveyard.
7. Repeat from step 2 as able, or until each opponent has milled their library.

This ingenious engine relies on Mycosynth Lattice to turn every permanent into an artifact, supercharging Mycosynth Golem so that The Cyber-Controller can be recast over and over for just three mana. Urza, Lord High Artificer converts your vast army of artifacts into a blue mana source to pay for those repeated casts while also providing an initial Construct token. Once The Cyber-Controller enters, its triggered ability steals your opponents' milled creatures as 2/2 Cyberman artifact creatures, and Krark-Clan Ironworks gracefully sacrifices The Cyber-Controller back to the command zone to clear the way for the loop.