I think bow naturally pierce, so I would remove both zenith from head/body, remove them and put another Glasscannon.
I think you build can't take a single hit, then why do you have taunt proc?
Change your amulet's talent to Deadeye and get an epic deadly strike on your pet. If you're satisfied with only 30% Deadly Strike, you may consider making another body with a different crystal affix.
A thing a learned in some guide in this forum is that crystal weaken >> ignore resist. I tested it and I'm actually very satisfied about it. You may consider using it too.
You can also add more elementcrit dmg.
I can't even see how you can survive at higher floors, don't you die too often?