I honestly dont know what percentage we are talking about in this game in any area damage or reduction one. I am guessing there will be some amount of each of them involved in Warhammer like in every other game. What I am saying there was not a single game that allowed to any character or item to be 100 resistant on any kind of attack. I am assuming that would be done in usual way how much damage and reduction is allowed to you totally depending on which class you are playing and how powerful it became during your game. Although there is possibility that mags and casters would have some advantage comparing to some mortal ones, which is logical I know, but sometimes completely unfair.