This is not a guide, just my opinion & questions w/ an open discussion.

I've read countless guides for mages.
From 100% INT = "Nuke Mages" aka "Glass Mages" because they die quick.
To STR/INT Mages for Tanking & AOE.
All of these theories is false and depends on your style of play.
IMO there's no such thing as a Tank-mage.
Mages aren't meant for tanking. Our starting health is 400. We aren't Bears.
They say STR/INT mages have higher survivability. WRONG!
I have a DEX/INT mage, 4k+ kills & 8 deaths. Deaths came from my ping spiking to 800+
IMO, I rather dodge than tank a hit. lol, who wouldn't?

Survivability starts from the way you play. If you play hit and run like I do then you're survive more.
For example, I cast BOM & BOV, run in a mob, Lightning - Ice storm - Firestorm, & run away, but not too far for the CPU run back & keep re-casting my skills.
Also skills will help you. (BOM, BOV, HEAL, COMBOS)

If you plan on "tanking" then your survivability is low. Heal + Magic Shield + BOV + HP pots won't last you very long if you're in the middle of a mob.

What's the point of being a 40/60 STR/INT mage? For more armor & health? It should be 60/40 instead so you can upgrade to STR armor for that LEVEL instead of being Lv30 w/ a Lv20-Lv25 STR armor.