Feranmut are living gods/spirits basically. Kjera is one (that is relatively weak I think?), its likely that Mostima's staffs traps another as well. I'm not particularly attached to them being Feranmut in particular, but I don't think we quite know whether other forms of spirits/demons/gods exist in Arknights? Beyond We Many that is. 

Anyway yea I'll just work on it first.