As someone who is playing a Mystic right now, your guide kinda cements a lot of things I was already feeling. A lot of the options for disciplines ae really not balanced with each other, feels like.

My idea was to go straight Wu-Jen discipline-wise, make a hermit kind of thing, very Avatar-y, with domain over the elements and stuff. RP-wise, start with the basic elements and work my way up to the more composite ones like Light or Ice. But Ice Mastery is ridiculous and tempting, while, say, Mastery of Fire is very much just a thing you get for Detonate (also Fire Form if you're melee, but I have a 10 Str gnome).

What I don't have the slightest idea about is items and equipment, though. I have legitimately no idea what to suggest to my GM for kinds of items I'd like on a blasty element Mystic.