Nerevarine cult
This is an ashlander cult. They believe they nerevarine will be reborn to honor ancient promises to the tribes. Will be cast down by the false gods of the tribunal temple, restore traditional ancestor worship practised by the ashlanders and drive all outlanders from morrowind. Both temple and empire outlaw the cult but it persists among the ashlanders who don't care about the imperial or temple law.
Prosecuted by the temple and since the cult is hostile to the empire the empire doesn't intervene.
They worship the Great Ashkhan and Hortator, Nerevar, Moon-and-Skar, who in ages past destroyed the evil, godless dwarves, and banished the treacherous Dagoth Ur and his foul hosts beneath Red Mountain.
The nerevarine cult is a small cult. With only a few wise women with the gift of phropehecy and a few holy warrior-heroes who guard and protect the seers. Sul Matuul, Ashkhan of the Urshilaku, is the warrior protector of the cult. And Nibani Maesa, also of Urshilaku, is the oracle seer.