I'm not as up on the dark arts as a future auror ought to be, I have to say. I know some things. I could stand to know a lot more--but it's pretty clear something hex-y happened. It was worse than a jinx, but doesn't seem quite as extreme as a curse.

So something that would affect emotions... Sounds a bit like a perversion of a cheering charm. Hmm. How did the fight go down? Did everyone erupt, or did a few people start at each other and then things just spiraled out of control from there? It would be useful to know if it was something cast on individuals, or if it was cast on the area.