if you don't mind, i don't recommend spellshield, and aura of guarding. they protect you till 140, but to be honest, i'd invest in other skills then this, as it's pretty bad protection for the five skill points.
The point with both Shield and Spell Shield is that they are very cheap to cast Mana-wise, and you can recast them as soon as they get low on hit points.
Spell Shield will also protect you from poison damage, AND stop those annoying little twitches poison causes your character to make.
As nothing in the game can take either shield out with only one hit, there is always time to renew your shields unless you are completely surrounded by very nasty creatures - and even then, the added hit points can make the difference between life and death.
