Personally, I didnt bother with Magic Shield at the lower levels. Its too much of a pain to recast every 40 seconds in normal circumstances. However, I find it very useful in the dojo and against bosses, especially with 2 evans around (-30% damage 100% of the time), and you might find some good uses at later levels. It will greatly depend on your play style though.
But personally, I found Magic Flare to be the better option at first. Its good for taking out straglers after you take out a mob, and its your primary 1v1 skill untill Killer Wings and Phantom Imprint.