Choukyoushi wa Mamono ni Kakomarete Ikite ikimasu ~Yuusha Party ni Oite Ikareta kedo, Densetsu no Mamono to Deai Saikyou ni natteta~ - Chapter 2

It took him that long to find out the true use of the fang. I already figured out since the beginning that he needed to use it like a wand to channel his magic.