Abasdarhon's Castle

I would join, but it clashes with the quest that Revan invited me to.
I'm already getting confused with the timing.
(And if we can get back there safely)

We're on the same page, but Revan has already sped ahead by two days, so if in-game days matter, then the next day is available for us, and we'll be on Hanzo's timeline after tomorrow.

I could potentially help with the mental entities if needed, but I don't know how to exorcise them, only "drain" them, in theory...

I was hoping for an exorcist to save a possible civilian, not just kill them. I'm ready to go solo and just kill them without exorcising and then cutting up the ghost, but that's not a great solution. Otherwise, I'm open to help if you want to go and have an idea on how to roleplay it.