Kanata Yanagino 
The Faraway Paladin (Manga) Volume 12 [EPUB ebook] 

Behold Valacirca, the eldest and mightiest dragon!

Will and his companions finally confront the formidable predator lurking at the heart of the Rust Mountains. The party think themselves ready, yet Valacirca’s attack is unexpected, striking at their resolve.

Faced with the choice between peace and death, Will must see through temptation to the sinister schemes lurking beneath. Only then can the true battle begin.