Pretty easy to make. As long as I know what the spell does... I can do this. But depends on the spell. 100% that I can do it for at least ONE unit/player but as long as I don't know what it does, I cannot promise that it would work for multiple units that belong to as singular player. ^_^
I can do the first part. Though I'm sure you are interested only in it. I can help you for one unit being able to cast it/player which means for heroes. Let's see... From what I've heard (didn't try it yet) it uses created unit and the "Last Created Unit" stuff. Well, you can do an array variable and usually give the array number the Number of (Owner of (Casting Unit)). Hope this helps you... If it doesn't, I will look at it. It's almost 11 PM here and I'm pretty tired. Heh... Answer me ASAP here, I will stay a little more online.
Didn't you read my notes? Well... I may change it as well and I guess Azure will not mind since I give it to you. I have absolutely no interest in doing that little change. Maybe you want it too Azure...
Phew... the map is done. Kinda fishy made and pretty... unconventional but it should work without risks as long as you give it to a single hero/Player. I know I could've done fors but even those could've caused errors because they needed variables and well... abusing people can pretty get past thema s well . HOpe it's good enough oh... and hope it works. I didn't try it . Make a backup of the original map just for sure.
Edit: Dang... I cannot attach. Gimme email adresses please...