Yooo I'm looking for something similar to Lord of the Mysteries and also My House of Horrors, No harem, or early romance The mc is decisive Not to op from the beginning Horror or fantasy
"Throne of Magical Arcana" is really good. It was written by the same person who wrote Lord of the Mysteries. There's no harem and it is a late romance. It is a fantasy/magic genre.
You should read sword of dawnbreaker The author of this novel and the author of LOTM reference each others work in the novel... plus the story is an incredible read