Fighting inside an arena, and in a real battlefield were two entirely different concepts. There was no concept of fair and unfair, and the only things restricting one's actions were the limits of one's creativity and ability.
Nothing Nero did was impulsive. Every action he took followed an outlined strategy he had decided long ago on how to deal with multiple enemy teams in close quarters. In summary, chaos and confusion were his friends, and he was determined to introduce them to everyone.
The reason Frostburn exploded as soon as the teams crossed the entrance was not to actually injure them, or to create hazardous terrain. If Nero left Frostburn burning too long within the fort, even his own teammates would be affected.
No, the real purpose was to block their sight and to distract them. Any damage they incurred was just a happy bonus.
