Skills, Items, Modify the effect by trigger (ex:dmg, life, Real Value of skill...)

How the hell can I modify the skill (real value) with a trigger (and variable) to like base the skill on stats or hero level. What trigger can help me to modify for exemple the bonus damage provided by a item or life or anything on item data.
How can I make damage with a trigger so the hero can use it with skills...
I don't know if you can understand what I mean but I will try to make you understand... I know its possible but I didn't find how.
I want to customise my item effect with trigger...
I want to use variable for the skills and item ability... :( :( :\ :\
Thank you!

Well I know that you could up the damage w/o much difficulty. Just make a trigger saying when a item is used (or rather a spell is cast, since most items cast spells, i think), do extra damage on the unit it was casted (or used) on. You could also apply a buff or increase life in the same manner.

I would like to find a way to make some hero skill effect based on the caster hero stats, a bit like in the EotA (EotA is like DotA or TOB, but with a lot more really nice stuff), do you know how can I make that, for the items I think I found way to do it... I will test it. Thank you for the help, but I think for the effect (ex: dmg), based on hero stats it won't really work...

I tried something with the items and doesnt work, it mean nothing work of what i try to do. :( :( :(

For the attributes you can check them with an integer--> hero - attribute. Example for an damage trigger.

Set life of target unit of abillity being cast to life of target unit of abillity being cast - strengt of your hero (exclude bonuses).

do it work with bounty or experience gained for killing creeps ...