(HELP PLZ) how to make ability that is dealing 3* attribute point

I saw on some maps that there are some spells that deals 3*Intelligence or 2* strenght (of my char).
How can i do that?

It is non-trivial. Basically, you make the spell with triggers so that the damage is completely coded, once you have that it is easy to make the damage based on an attribute, or hero level or whatever variable you can come up with.