This ingenious engine turns a humble artifact imprint into a self-sustaining loop by weaving together the passive traits of March of the Machines and Intruder Alarm. Because March of the Machines transforms Soul Foundry into an artifact creature, it joins the battlefield's ecosystem of creatures, allowing it to untap whenever Intruder Alarm triggers. When you use Soul Foundry to imprint and repeatedly stamp out a zero-cost Phyrexian Walker, every single copy's arrival triggers Intruder Alarm to untap all creatures—which includes the newly animated Soul Foundry itself, ready to be tapped right back away for another iteration.