You can use your spells while paused, and for the very last fight with a bunch going on at once, this makes it SO MUCH easier. I struggled at first, then just repeatedly kept pausing to use what I needed where and when. I can only imagine the grinding or skill needed to pull this fight off otherwise.
"The day is finally over! You relax for the first time today and settle down to enjoy the warm, cozy bed."
Ah, the warm, cozy bed, that's what this is all about.
I can't believe it took me so long to figure it out.