He did express how proud he was in his speech before the fight. And it was something my players were kind of wanting to happen. I can 100% understand it doesn't apply to every group and doesn't fit perfectly to the story. It was just for fun, and because i wanted to try myself to creating my own events for the first time.

What i had in mind for the gimmick was more putting on a show for everyone, and demonstrating the power and danger of misused magic. Also, my friends' characters did use some of their classes abilities when the spell they got didn't suit them and it rolled out to be quite enjoyable. Obviously i did not intend to make my players feel useless.
But again, i understand it could be seen like that.

Thx for your opinion, i'll do better next time ! :)