Respond to attacks with a custom spell

[Super-Human]

I need help, yet again -.-. Remind me not to take a few months break off mapping :S lol. Well, my question is HOW can I make a unit respond to an attack with a custom spell?
This is what I have so far:



Events:
Unit - A unit is attacked

Conditions:
And - (All conditions) are true
---Conditions:
---(Unit type of (attacked unit)) equal to *insert name here*
---(Mana of (attacked unit)) equal to or greater than 100

Actions:
???



I want this unit to cast a custom version of a spell. The unit has this in his abilities list. I had a look through "Issue an order targeting 'so and so'" but it's obviously not listed. Any ideas? I hate using the AI editor, is there any way to do this using triggers? If I can't do this, my whole map is ruined. Pity I spent over 1 week on the terrain .

 

[Mini-Me]

You order the unit to cast the spell which the custom spell is based on.

Example: You got spell Fire Wrath, you made it by modifieing shockwawe.
Solution: you order your unit to cast shockwawe, and he will cast your custom spell Fire Wrath.

 

[Super-Human]

Oh right.

Ok I made it cast (No Target) Orcs (I think it's orcs :|) Berserk and it worked. Thanks for that.