Retrofitter Foundry + Ashnod's Altar + Clock of Omens + Primal Vigor

Retrofitter Foundry

Ashnod's Altar

Clock of Omens

Primal Vigor

How it works

1. Activate Retrofitter Foundry's second ability by paying 2 and tapping it, creating two 1/1 Servo artifact creature tokens.
2. Activate Clock of Omens by tapping the Servos, untapping Retrofitter Foundry.
3. Activate Ashnod's Altar by sacrificing a Servo, adding CC.
4. Repeat.
5. Once you have infinite mana, you may instead use Retrofitter Foundry's first ability to untap it and get infinite untapped Servo tokens.

This engine gets its incredible leverage from Primal Vigor, which doubles every single token you create to turn a modest investment into a net-positive loop. By using Ashnod's Altar to sacrifice one of the newly minted tokens for mana, you fuel Retrofitter Foundry while Clock of Omens taps your artifact tokens to keep the Foundry fresh and ready for more. The magic of the Clock of Omens and Retrofitter Foundry pairing means you never even have to worry about tapping out your engine pieces permanently, letting you effortlessly churn through your artifact creatures to generate infinite colorless mana and an overwhelming army of tokens.