Well, right out of the gate, let's get ALL the Suffering References down pat, as Blackgate island is pretty much Carnate only without a prison quarry used to make the walls of the actual prison from the native rock of the island.
So, we need various manifestations of execution or horrible horrible death (Beheading, Firing Squad, Lethal Injection, Hanging, Live Burial, Incineration, Eaten by Rats, Electrocution, Gas Chamber, et al, if you're going for the classic set from Carnate) and, potentially, rumours of some giant thing spoken of only in whispers and called THE BEAST.
Of course, considering that Stan Winston (aka; the guy that made the Terminator and the Alien Queen) designed each of the malefactors that first appeared on Carnate (and later, the streets of Baltimore), well, not much can be said to add to the physical descriptions.
Now, if you want something more along the lines of incarnations of emotional, mental, and sexual abuse, well, that's where King, Silent Hill, and Siren come into play; Lots of creepy noises, lots of slow-build scares instead of jumpscares, and, of course, human characters that make the hideous monsters look personable and charming. In fact, I'd guess that Nurse Ratched is in charge of the wards, too.