Re: Acid damage and Bane Fire damage
 

The armour destruction can make it useful even so, I think. Destroying all non-item shields on the battlefield can make archers a lot more effective.

Re: Acid damage and Bane Fire damage
 

Except how are you keeping your archers alive?

Re: Acid damage and Bane Fire damage
 

In theory, if you have some regenerative effects on your troops/mages, you could nullify the effects of acid storm.

With Jomon, for example, you could potentially bootstrap one mage to cast acid storm while another casts mass regen. You can have even more mages boosted to cast blade wind to take advantage of damaged armor. (And while you're at it, those same mages can also cast mass protection to help mitigate the damage)

Not saying it's an incredibly viable strategy, but there are some synergies to go around.

Re: Acid damage and Bane Fire damage
 

Human mages can't really cast acid storm successfully, unless you're just after the armor destruction effect. They tend to die messily after a few rounds since they get critted to death from the casting fatigue, and there's no way to get immunity to it.

Re: Acid damage and Bane Fire damage
 

I don't think you would generally use a human mage to cast Acid Storm. It's 4WF paths and costs 3 gems... I would use a Water queen or something with regen/high hp or high %-regen. It would be pointless to use a regular mage. The regular mages should be good to go with a nice volley of Acid Rain (AoE 4+ only 30 fatigue and 12AP).

As for the fatigue, bring along a sacrificial lamb (Communion Slave) and kill it. Any cheap astral mage will do--Star Child, Theurg Communicant, etc... You'll just need a master matrix for the caster and it will be necessary that your slave be higher on the casting list than your master which could get rough unless you don't mind waiting until round 2 to cast it.