That was intense.
My only concern was that the frames were skipping forward a little too fast. It felt like having a tween-frame in the middle of each one, just to smooth the animation out, would definitely give it an edge. That's the unfortunate thing about "fast" is that is absolutely must be "smooth" as well.
Nevertheless, that was, indeed, insane. Artwork was superb, and I could name off all the attacks they were pulling off, which includes an undead thumbs-up for credibility.