Ok look at it this way, any spell that is cast directly at 1 unit [although it may affect others], allows the unit to use its MR if it has any, and that is ANY spell at all and that's taken from the rulebook. Spells which target the caster, ie howler wind and warrior priest abilities obviously don't allow for MR because the caster is the target, not an enemy unit.
I am sorry, but this isn't rocket science, its really a matter of reading the rules and taking a common ground interpretation, and while the original question is a good one, it isn't that complicated to find the answer I feel. Bear in mind that the books from 6th Ed that have not been re-released will have difficulty with some magical items/attacks due to the subtle changes in the wording of MR in the rulebook and effects that will not be the same in 7th edition army books compared to their 6th edition counterparts.
Dain.