Before I proceed, I should warn you that this post may contain spoilers. I have been keeping track of the manga version of My Hero Academia and I am deeply intrigued with the transformation of Tomura Shigaraki.
After forming the Paranormal Liberation Front, Doctor Ujiko promised to make Shigaraki even stronger through a complex surgery. This process was said to last four months and be indescribably painful, but the rewards are worthwhile because it could potentially make Shigaraki even stronger than All For One. We saw how powerful All For One was during his final battle with All Might and he was way past his prime. The thought of Shigaraki being stronger than that, combined with being able to disintegrate an entire city with a single touch, would easily make Shigaraki the single most powerful and dangerous supervillain in the entire story.
In recent chapters, I saw Shigaraki get hooked up to a series of tubes and wires with Doctor Ujiko cheering from the sidelines. The surgery looks like a combination between the surgery that gave Wolverine his adamantium skeleton and claws as well as the surgery that got Bane hooked to the venom super-steroid. As we learned from Izuku Midoriya, when a person receives an unnatural power, their body would either be damaged or destroyed from the extreme kickback. Considering Ujiko is making Shigaraki stronger than All For One, the power Shigaraki would gain could kill him. With this in mind, I believe that Shigaraki’s body will receive a series of physical upgrades and augmentations that would allow him to withstand the extreme kickback of his new power. Once those modifications are done, Ujiko would then proceed to implant the power or powers that would make Shigaraki stronger than All For One. However, like physical therapy or adapting to an organ transplant, I think Shigaraki would need time to get used to his intense changes. That could explain why Shigaraki’s surgery would take four months to complete.
However, due to the most recent chapters, Shigaraki is at risk of awakening from his surgery a month too early. If that happens, Shigaraki may not be able to complete his surgery and his true strength may not be realized. Either that or his body may not have fully recovered from his changes and his new power would be dangerously unstable. However, if Ujiko and his High-End Nomu can fend off the heroes and give him and Shigaraki a chance to regroup to another location, then Ujiko might buy enough time to complete the surgery. We shall see as the final war between heroes and villains begins!