Mages do not need more defensives lol.
Not only are they supposed to be a Glass Cannon, hell they literally have a PVP talent called that, but their existing defensives are already strong.
They have Ice Block which speaks for itself.
Blink/Shimmer which is a crazy OP escape tool.
A bunch of movement control spells (snares/roots/dazes/knock backs).
A hard CC (Poly) which can be spammed.
The ability to remove curses.
Alter Time which is a health and position reset.
A cheat death (Cauterize)
Barriers.
Invisibility.
Mirror Images.