Quote from ZeShmoutt: Go
I used the catalog trigger at first, it was fine until my brain screamed "OH GAWD IT SHOULD BE FUN IN MULTIPLAYER, too bad catalog method is bad for that, eh ?".
Catalog triggers work perfectly fine in multiplayer, but the changes are applied to all abilities of the player. Abilities casted by other players are unaffected.
So if you don't use multiple instances of the same ability for the same player, which can have different attribute bonuses, you should be fine.
Also, upgrades do exactly the same thing, they are the data equivalent of catalog triggers.