Don't allow "someone" to spawn adds when fighting bosses.

I was fighting an optional boss and suddenly someone spawned an orb weaver and two scorpion babies. It was a fair fight and hard enough as it was, but this was just unfair. It might make sense story wise but it's really annoying and can disrupt boss balance. 

Make it so they can't summon enemies in boss areas. I can only imagine how horrible it could be with a bosses natural adds and then someone throwing even more into the mix.