Give me your email and I will try to send you the map once I make it. Though I don't understand what's so difficult to simply apply the trigger I screenshoted into your own map. Copy it EXACTLY how it is there and then change the following stuff:
->Instead of Creating 1 Footman you will need to create 1 Dummy Unit (I hope you know what dummy units are)
-> When you "Order (Last Created Unit) to Damage (Picked Unit) for (50*Real(var)))", you can change the 50 to whatever you want (the damage multiplier... In your last example, 100). One more mention, the Real(var) is actually the function "Convert Integer to Real". Damage is Real and the number of units is Integer.
-> var is an INTEGER Global Variable
-> At the Conditions, you will need to change the "(Ability Being Cast) Equal to Cluster Rockets" with your own ability (the one you give to the unit you want to have the ability itself)
Of course that BASIC spellmaking requires BASIC knowledge of triggers. If you still can't work with triggers, you can play with them for a while until you get the whole hang.
~Daelin