Mother Ostankya is a series of slightly annoying decisions

>binary choice between being locked out of 90% of Kislev units, or having total access to the roster
>gimped if you choose to stay in Naggaroth
>participates in the Ice Court vs Orthodoxy for no reason
>trains Ice Witches instead of Hags

She should have her own "Old Faith" vs Orthodoxy mechanic that lets her slowly unlock the roster as she converts more of Kislev away from the Orthodoxy back to worship of nature spirits. Also Hag school.