The location as seen in game
Forsaken Repose is an area accessed from Greyhollow Island in Act V of Diablo III, in Adventure Mode only. It can be accessed through a purple portal from Testament of My Failure tomes, once players find both parts.
It is a special version of Ancient Tower Battlements, but other parts of Ancient Tower cannot be accessed from it. Corpses of Nereza and Sara are still here.
A special unmarked event occurs when players step through the portal. The area cannot be left until this event is over.
The Crazed Man will appear and, when spoken to, will plead the character to cleanse his soul. He will then start combat, gaining extra abilities. Once killed in mortal form, he will shift to his ghost state, and must be killed anew. Finishing him twice concludes the event, releasing him from his curse and opening a portal back to the island.