Need Help With Trigger

Ok. This what i wanted. Is like i already modified Granite golem attack to be the rock skill that they throw. But i wonna do a stunning also. this what i got so far

Event: A unit owned by player X is attacked

Condition: Attacking unit = Granite Golem

i want 25% of being stun. the action i think i know abit

1 - 10 if equal to 10 then create special effect _____________ on attacked unit overhead i can figure this out Set Stun = Last special effect. pause attacked unit. wait 6 seconds Destroy Stun.
Unpause attacked unit.

Can someone help me on the 1 - 10 if equal to 10 part? I dunno where the trigger is. so can anyone tell me a full trigger what i try to do?

Event: A unit owned by Player X is attacked

Condition: Unit-type of Attacking unit = Granite Golem

Action:
_________________________
Create _________________.mdl overhead of attacked unit.
Set Stun = Last Special Effect
Pause Attacked Unit
Wait 6 seconds
Destroy Stun
Unpause Attacked unit.

I been wonder also. Like this. If = to 10 then turn on this trigger. Otherwise i been wondering it just do this everytime attacked unit get hit it just get stun.

First, you use the action If/Then/Else and have the "If" set as Math- Random number. The then would be the stun and special effects and what not. The else would be Do nothing. Oh, I don't think the special effect part of your trigger will always work. If your golem attacks two people in within six and bashes them both, only the second special effect will be destroyed. (because you reset "Stun" as the second effect)

Please send me a full trigger.

Create a variable called "Random"
Set Variable "Random" equal to a random number between 1 and 10.
If "Random" is equal to 10 then do (what you want) else do nothing.

Event: A unit owned by Player X is attacked

Condition: Unit-type of Attacking unit = Granite Golem

Action: If((Random integer between 1 and 4) Equal to 1) then do (Do nothing) Else do (skip remaining actions)
Special effects- Put on that special effect, I'm sure you know how.
Set Variable- Bla bla.
Unit- Pause (attacked unit)
Wait 6 seconds.
Unit- unpause (attacked unit)
Special effect- destroy (stun)

I think that's it. Except for the problem about the special effect not disappearing sometimes, I'm too lazy to put a solution on that.