Horrible Horridon gave me a horridly horrendous headache. I just had to say it. 🙂  *Ahem* Horridon is actually a really fun fight that requires a lot of coordination from the raid. If everything is executed well, it turns into a lovely clean polished boss kill that can be rewarding.
This is mostly a two phase fight with the second being the final burn phase. The first phase involves dealing with waves of troll adds of different shapes and sizes and having the right dps priority in getting them down.