KONOSUBA - God's blessing on this wonderful world! (2016)

S1E4 Explosion Magic for This Formidable Enemy!

With the appearance of a powerful leader from the devil king's army, all the weaker monsters have retreated, leaving the town in a state of unease. In the midst of this, Kazuma finds himself stalled in his skill development. Seeking a distraction, he joins Megumin in her explosive training sessions, which involve practicing her explosive magic at an old, deserted castle. Together, they unleash her powerful spells, hoping to prepare for the looming threat that the new enemy poses.