Enquiries of the Cerebral Sanctuary

This book is torn/stained pretty badly. Some of the pages are missing. It is written in Elysian Speech. It has metal hinges and clasps. Records of investigation into a an organisation called the Cerebral Sanctuary.
When the whispers of Harald Josson's work had reached the Institute, it was understandably met with head shaking and denial. But as we act upon every potential, regardless of the ridiculousness of the notion, I was tasked with following up the paltry lead of information and uncovering whether Josson's reports were indeed turhtful, or even if there was a small percentage of factual reasoning. It seemed only prudent that my investigations and enquiries began at the Cerebral Sanctuary, a governmental institution that was essentially beholden to the incarceration of those of madness. Suggestions from political enemies of Tosima remark that those without ailments have been sent there to be forgotten about until their eventual passing.
Using simple enchantment magics, it was a simple enough thing to volunteer my entry as a patient to the Cerebral Sanctuary with the aid of Klaxoth's illusory magic. There is without doubt, a unforgiveable treatment of those within the Sanctuary. The very name would bring tears of laughter, if tears of sorrow and pity did not already fall upon cheeks. Ailment or no, these were still people yet were treated as animals in a pound or convicts in a prison awaiting their sentencing. The staff within the Sanctuary seemed to take great pleasure in the unjust treatment of the patients they were charged with caring for.
Following the leads of the found articles and whispers form those chasing the tail of Josson, there were five people who met the description, in their eternal madness and belief in their perceived ascension to godhood that awaited them. There was an oddity, however, is that the illness that has struck them has somehow led them all to Elysia, yet not all were born within this world. One from Oerth, another from Faerun, one from Eberron, one from from Elysia and the last from Courrakey. Whilst not all were from Elysia, they all believed that they would find their salvation within Elysia and were drawn to this world to recover lost powers.
Perhaps some would consider it ill advised, but I encouraged their behaviour in the hope of gaining their trust and seeing what information could be gleamed from them. If the research were deemed true, then these poor creatures knew nothing of it. They were completely and entirely sold onto the belief of their untold powers. Whether or not there was truth to the findings or not, it did seem clear that they were not threat to mankind as long as they were within the Sanctuary.
The above conclusions proved to be untrue when two of these believed fragments found themselves to be at odds, professing that one had insulted the other in this life and the last, leading to brawl within the Sanctuary. Alchemical injections proved to have little effect on the creatures, and only appeared to enrage one of them further. As when conjured a ball of fire in its hands without components or focus, another conjured lightning in the same fashion in their battle. To my surprise and all those who trembled in fear, I watched as the tissue and skin of one man's flesh tore and ripped, unearthing red fur and blue skin as it changed form in what could only closely described as the Tanar'ri Demon commonly known as a Barlgura. Use of my enchantments to clam the creature fell upon deaf ears as the wave of carnage grew as the creature swatted away patients and guards like flies. In nature and appearance it was unquestionably similar to the Tanar'ri, but its power and constitution far exceeded my experience of the creature during my studies of the Abyss.
A regret I will hold for the rest of my days was turning the creature to ash. He had no idea what he truly was, and was beholden to the essence inside of him with no control of his actions beyond the last conscious thought before his transformation. With my cover unquestionably blown, I was able to decree with the permission of the Tosima family that the remaining creatures be placed in solitary confinement in the deepest most secure dungeons of the Sanctuary until their dying day. If these creatures were to escape and find their way into civilisation, they are a demon in sheep's clothing and set to wreak havoc upon the world with no control over their form or actions.
Any remaining Fragments of the Fiend Lords must be found, locked away or given a death as merciful as possible.