Favorite build so far! I've been using nearly the same set up and it works great for me. Personally, I put the wither and leech points into suppression rather than pain. Like others have said elsewhere, the damage gain (of pain)is marginal at higher ranks and the explosion damage doesn't change. It may not mean much to some but 1 or 2 extra stunned mobs are worth it to me.

Nice job on the playing tips/technique, too.