Can you use the metamagic of shielding even while taking an exclusive action? I know it's not possible for spell defense, but I was wondering how it worked for shielding..

Also, what are the advantages of shielding over spell defense ?? Is it that shielding gives dice to be used by EACH person protected and that casting TNs go up ? I just want to make sure I understand shielding correctly.

I would imagine exclusive means no other magical action, period.

Shielding raises TNs as well as providing extra dice for resistance.

Not sure about the persons part of the question.

Shielding (as well as absorbtion and reflection) is an enhanced version of spell defense. The advantage of shielding is that it also increases the TN to any spell directed at someone under your shielding. Anything that prevents spell defense prevents shielding. If any detail is not explicitly stated in the shielding description, it is the same as regular, non-meta-magical spell defense.

IMHO shielding doesn't require the magician to perform any magic action, and therefore it could be done while performing an exclusive action. That's just my personal opinion.

Another advantage of Shielding is that the dice are not used up, like Spell Defense dice. They can be used as part of the spell resistance roll for multiple spells in the same Combat Turn.

On careful reading, there is no requirement as to when in the action shielding can be restarted for the next time period. Therefore, it is a valid interpretation that you can perform an instant exclusive action and restore the sheilding immediately after.

By contrast, I do not see wording that would imply you can use sheilding during an extended exclusive action. Spell defense doesn't require an action either, but is still forbidden in such cases.

After reading your answers, I feel that Herald of Verjigorm has the best explanation. Thanks to all for your view on this.