OK, let me try to explain it more clearly (I fail in it usually, sorry).
You need to make such triggers that double damage (just for example, it can be 20% or something) inflicted to your hero if he/she has Rage ability. So triggers work like this: when someone hurts someone, you check if the hurt person has this ability. If he/she has it, triggers double this damage.
So it would be very easy to write something like this:
Event->Unit takes damage
Condition->Unit has Rage ability
Action->Set unit's life = unit's life - (damage taken)
This would double the damage. Easy, right?
Not so simple. Unfortunately there is no such event "Unit takes damage". But there is an event "Specified unit takes damage". The difference is the first event (if it existed) would work for every unit in the game, while the second one works only for a single unit you specified.
So what you need to do is to make this event for EVERY unit in the game, so that any of them has Rage ability, the trigger will work for him/her.
That is where that trigger with a cycle and the action "Add event to trigger" comes into the game.
This is all for taking more damage by this ability. For inflicting more damage in my test map the command aura is used (with modification, it is called Passive Rage).
If you wish, you may paste here your map and I will implement this script there.