Medusa, the Restorative Mind

"'Your 'army' was eradicated by Medusa, one of the Restorative Minds. You attracting it was a mistake, you are the only version of yourself to escape your reality. Incomplete, you are undoubtedly a false creation. The Restorative Minds reputedly possess the ability to define what is and is not real. Whatever they perceive becomes subject to erasure at their will. Until a countermeasure can be found, you must avoid their gaze at all costs. If you had stayed any longer within that simulation you would revert to the data streams and be reconfigured elsewhere.' - Simulated [CRAS/6742103/ Macharius]"

Medusa, the Restorative Mind is a Palace Mind encountered across faulty simulations and mainly resides within Simulation 1. Restorative Minds like Medusa are deployed when a significant node of the Palace's network is altered; in Medusa's case, its purpose is to re-write and hunt down rogue simulations. As one of the Restorative Minds, it is described as being an "ontological weapon": beings capable of rewriting reality to its advantage. Its abilities are apparently limited to the Palace, however.

Appearance
Medusa is described as a 'great eye' sitting in the centre of three shifting pyramids and is one of the largest Restorative Minds, possessing the size and ability to easily re-write entire cities (within the Palace) in one fell swoop. It also is known to let out a metallic wail each time it re-writes a section and has been none to be effectively impossible to kill through simulated weaponry.

Encounters

 * Currently, the only time that Medusa has been seen is within Simulation [CRAS/456201732/DECIET] where it nearly erased both Kliridotó 2781 and Macharius 87213214 before they are saved by the 'free-willed' Macharius 6742103 who simply refers to himself as Thomas. It manages to eradicate the entire corruption facing the simulation apart from those two simulations and marks 2781 as a major target.
 * As Thomas also seems to know much about it and references its power, it is safe to assume that he has also greeted the machine at some point across the timeline.