Act 1: Part 9 -
Tried to search first, got nothing. So here goes. One of the most difficult bosses due to the burn phase.
After 3 minutes of battle the floor begins to ignite at all locations, making it nearly impossible to kill the boss.
I found however if you go to the very bottom of the map, there is a ledge on the south most part, where you will remain unaffected by the fire.
This will allow you to stay alive for a few more minutes if not more, definitely not working as intended.
Thanks,
-beck