To me adding all of that extra time to the game seems like it would just get boring. I’d rather play 7 minute’s of good game play instead of 7 hours of repeating the same strategy over and over again.
Perhaps a physics based puzzle would spice things up. Like after you get teleported to a different area of the map (because stacking boxes while the Nihilanth would suck). And to add to the complexity of the fight, instead of an open arena, perhaps the level should consist of small changes in elevation so you can’t just sprint to one side of the map to the other without jumping over something (another words you have to take your eyes off the Nihilanth to see where your going). Adding props instead of spikes would also add to the visual impact of the level as well (but that’s probably asking too much if the devs are sticking to the original level design).