[Xietor]

It depends.

if your enemy has a lot of flying troops(Pythium angels, Marignon, angels, Pangaea, swarm, blood nations, imp spam, devils), or you are facing deadly missile fire or flaming arrows, you may want to cast storm. But if it is just missile fire, you are better off casting arrow fend, not storm.

But you need to protect your mages. And if the enemy is getting his flying troops to them quickly, you may have to use storm. Note however that air elementals and some other
flying units can fly even in a storm.

Storm does not effect 100 precision spells. So if you have astral mages, storm typically will not hinder them. Drain life, frozen heart, incinerate, and other spells that are 100 precision should be scripted if you are using storm if possible.

Or you can use evocation spells that hit such a large area that storm will not effect your mages too much(niefel flames). Make fure your n and a mages cast eagle eyes and aim as their 1st spell if you do not have the gems or research to get wind guide up.

These same tactics are also good against Lanka and other nations when they cast darkness. Lanka typically casts storm and darkness, so you really need to use items and spells with 100 precision to kill stuff.