Obviously this is a bit strange, but what if it were possible to have a basically immune Wizard Support?
W1 - C1 - L2 - Thaum 3
Cryomancer Passive attribute gives 125% of your Shield Defense to Magic defense and Ice Property Defense.
Wizard Gives Lethargy debuffs + Slash buff.
Linker 2 gives you better grinding + group appeal.
Thaum 3 gives +271 Physical and Magical defense with a Shield.
2x Elements Dance gives +294 Fire, Ice, Poison and Lightning defense properties ( -210 Magic Defense ).
Guardian gives +25 Fire/Ice/Poison defense.
Aspersion gives +68% defense?
With decent gear/ehances, your looking at around 1400 physical defense, 1000 magical defense, 500 Ice Resist, 325 Fire/Poison/Lightning resist.
Even a boss in one of the resist stats will hit you for peanuts.
You can stat pretty much anyway you want.
You have decent group appeal being L2 + Thaum 3.
Just a thought.