Lightniing is uncommon enough to warrant a lesser immunity IMO.
brawl... yes, I guess it is possible. How did you get such a weird immunity? Major, in any case. I would say that you are immune to brawl damage but not to the impact itself. So you can fall if pushed and turn your face if slapped, but you take no damage out of the hit.
@ExarKun:
No, 'magic immunity' is not an option IMO.
Try:
Immune to mental control (or downright stubborn).
Immune to fay (two-way would be nice, ie. he can't do anything to fairies either).
Perfect body (immune to corpus warpings).
Or just take a bloody high Parma Magica (using the affinity and puissant virtues).
Other ideas:
Immune to alcohol intoxication
Immune to warping from aura's (and only aura's, not warping in general!)
Not affected puppy eyes
Immune to stinging plants (like nettles)
Not affected by the headaches from dominion aura's
Wounds never get infected
Immunity from Primi