The army has 7 dispel dice, do you think I need dispel scrolls? I know its not a lot, but half the time they are only going to kill clanrats or slaves.
Need is a strongly debateable word. Im not a fan of many scrolls myself but one can very often come in handy. Either against some "one use arcane item" or when the opponent rolls 23+ on 5 dice for something bad. But in general your magical defence will probably be enough.
Oh btw a Warpstone Charm on 1 character can really help out, specially on the engineers since Warplightning frequently rewards the caster with wounds