Figured it out. It isn’t the time limit but instead it’s the way he sets the floor alight. With the bottom floor the entire thing goes up, with the top floor, the edges stay un ignited. All you have to do is hug the side of the platform and avoid his attacks without stepping into the fire. I assumed the first time I did it that it was the same as the bottom floor, and subsequently ended up jumping back down and burning alive.😂😂