I'm looking for a specific manger i started reading but lost it as i was too dumb to save the details years ago

The only chapter i remember had it starting with a woman and what i'm going to assume was a sorcerer, wearing a cloak and hood with his face covered, imprisoned in an alternate dimension. I believe the cloaked man was her subordinate or henchman, and the woman herself was some kind of threat to mankind. The chapter ended with her henchman breaking the dimensional barrier or something like that and showing he was actually more powerful than the woman. Unfortunately i don't remember what the woman looked like at all.

pic is unrelated but a similar style to what i remember.