So the fights as they stand are:
- Kai and Noel vs East 11 on the mansion grounds.
- Shoggoth vs Scarface inside the mansion.
- Nyarlathotep vs Ithaqua and other Directors at Far East HQ
Now I don't expect to see much of the fight between the Directors. That's the sort of thing that will probably take place either mostly or entirely off-panel. Ikeda will certainly want to keep the capabilities of his top tiers mysterious for now I'd imagine.
I note the conspicuous absence of Dr West in the last few chapters. As Shoggoth is present (she is his familiar after all), I can't imagine he's far away and will likely be key to turning the tables here. His zombies could keep members of the East 11 busy so team Ghost Reaper Girl can divide and conquer as it were, but first he's gonna have to get Scarface away from Chloe.
So Oscar C'thullu is confirmed to not just be Kai's original master but, because the master/servant link was never broken, he is his TRUE master. Kai apparently did all kinds of evil with Oscar. Oscar being so powerful he was once called a "Dark Lord" feels like a nod to Rosario where the three top tiers were called Dark Lords.
Kai/Yog's full power will likely be on par with the Directors at a guess (given how worried they seem to be and the lengths they're going to get rid of him) but as he's linked to Oscar, it gives an excuse to keep Chloe from getting too overpowered (she likely wouldn't even be able to use his full power right now anyway).
Anyway I hope we get a good showcase for each member of the East 11 here and they're not just fodderized by full power Kai.