Breya, Etherium Shaper + Master Transmuter + Phyrexian Altar + Intruder Alarm

Breya, Etherium Shaper

Master Transmuter

Phyrexian Altar

Intruder Alarm

How it works

1. Activate Master Transmuter by paying , tapping it and returning Breya from the battlefield to your hand, putting Breya onto the battlefield from your hand.
2. Breya enters the battlefield, triggering itself and Intruder Alarm.
3. Resolve the Breya trigger, creating two 1/1 Thopter artifact creature tokens.
4. The Thopters enter the battlefield, triggering Intruder Alarm twice.
5. Resolve all Intruder Alarm triggers, untapping all creatures.
6. Activate Phyrexian Altar by sacrificing a Thopter, adding .
7. Repeat.
8. Once you have infinite creature tokens and infinite colored mana, you may activate Breya's ability infinite times.

This clever loop relies on Master Transmuter constantly cycling Breya, Etherium Shaper back to your hand so she can re-enter the battlefield and spawn a fresh pair of Thopters. Every time Breya or those Thopters arrive, Intruder Alarm triggers to untap your entire board, allowing Master Transmuter to stay ready and untapped for the next iteration. Meanwhile, Phyrexian Altar neatly turns those sacrificial Thopter tokens into the exact blue mana needed to pay for Master Transmuter's activation cost while generating infinite mana and death triggers along the way.