My question is more complicated; I think, how do I code new attributes? What I want to do is not covered by any of the available attributes.
Another question, where are the "mult_onhit_enemyspeed" sort of files located. If If scroll down on the items file I find another set of parameters for that specific attribute, but nothing that can be changed. Even if I can't create new attributes, I would like to know how Valve created those crazy attributes.