Retrofitter Foundry + Ashnod's Altar + Clock of Omens + Bard, King of Dale

Retrofitter Foundry

Ashnod's Altar

Clock of Omens

Bard, King of Dale

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 clever loop relies on Bard, King of Dale's powerful replacement effect, which doubles any tokens you create to turn a modest start into a massive surplus. By using Retrofitter Foundry to churn out Servos that are instantly doubled, you create enough hardware to fuel Clock of Omens for infinite untaps and Ashnod's Altar for infinite colorless mana. Once your mana engine is fully operational, Retrofitter Foundry's first ability can be repeatedly activated to untap itself directly, leaving you with an unstoppable army of infinite tokens.