the big downside to your build is defense. moving to keep monsters targeting you often is a good thing to do, and in emergencies, you can use Shatter to get out of a bad situation.
here is a helpful tip for your Skull:
use Diamond to get Fire to +100%.
then use Obsidian to get Crit DMG to +225%. (you need an empty space on the Item to do this, so take off the CB or MP on Hit, you can put them back on later)
then use Fluorite to maximize HP on Hit & CB.
Glasscannon & Empower are similar in that they both increase DMG.
Glasscannon increases DMG +50% but lowers HP -50%. if you have +100% Glasscannon, you will have 1 HP.
Empower increases the Wizard Power Stat by +2.5% per Rank while reducing HP -2.5% per Rank. with Empower 40, you would increase your Power by +100% and only have 1 HP.
example: Empower 20 increases Power +50% with -50% HP. with Power 50 x 1.5 from Empower, Power is now 75. Empower 40 with Power 100 would give you Power Stat 200 with only 1 HP. (each Power Stat is 75 DMG)
you can use both together, and HP will only go as low as 1 HP.
if you are wondering how the Power Stat works, here is a Post I made.
hope this helps.