For the most part, Sephiroth was pretty easy on Proud Mode. The thing I liked doing was reflecting his fire walls. That takes a chunk out of his life.
That's one funny slideshow, though it hurts my eyes. xD
I would continue using those brushes if I were you because those are pretty cool brushes. What I meant is that you should try other effects WITH the brushes.
Oh, sorry. Anyways, the brushes are very nice, but you shouldn't rely on brushes so much. Try some other effects as well to enhance your tags/pics.