Doufu Mayoi 
Black Summoner (Manga) Volume 18 [EPUB ebook] 

“Nah, we should liven things up instead!”

It’s time to assault the Catacombs of the Heroic Spirits! Members of the Elearis cult have kidnapped people from the orphanage and occupied a dungeon. Now, Kelvin and his friends have the job of rescuing the hostages while bringing down the cult—an especially tough prospect given that Reviver may be manipulating everything from the shadows!

Our heroes hatch a plan and put it into action, but unfortunately, even the best laid plans rarely survive reality, and things quickly go awry once new enemies start to show up on the lower levels: major figures from the distant past and…a dragon?!