Institute of the Gods (S02E15)

Erdomaid trains the students in methods of dragon slaying. He does so in a dangerous battle with an actual dragon summoned. Anos and his friends infiltrate the dragon’s den and arrive in the Underground World, where the dragonfolk called Draconids live. Ahide, who attacked the previous evening, guides them to the Institute of the Gods, Everastanzetta. There, Anos is told how he has already been involved in the “Judgement Selection.” (Crunchyroll)