Scripts

It won't work. It's hard to explain, but the combat script functions imply a single action/cast. Here, there are actually two (selecting the type of arrow + selecting the spell). This means there isn't a suitable function. For the same reason, you can't cast teleport with a script (selecting the target + selecting the location). But you can try to emulate the arrow action – first, cast "Rain of Arrows," and then the desired spell on the units that will take damage after the volley.

It won't work. It's hard to explain, but the combat script functions imply a single action/cast. Here, there are actually two (selecting the type of arrow + selecting the spell). This means there isn't a suitable function. For the same reason, you can't cast teleport with a script (selecting the target + selecting the location). But you can try to emulate the arrow action – first, cast "Rain of Arrows," and then the desired spell on the units that will take damage after the volley.