Well, it's kind of like you choose your class (and maybe your spec) and your abilities should make sense in accordance to that class (like, you don't have an ability that makes you shoot faster on a scrapper or something), but as long as it makes sense, it would be alright (like, if you want to make a tank shoot lasers our of his eyes, you can have him be a half cyborg avatar with cyborg abilities). At least, that's what I got out of it.