I don't remember which, but it was either that you have to have atleast 3 in every tree, the rest you're free to spend as you wish or that it was just unwise not to have +abilities in every class.. Eh, who gives a shiet
You only get universals until level 5, THEN you start unlocking class-specific abilities - so until that point you'll only get abilities you can use with every class. You're never forced to take class-specific abilities for a class you don't care about. EVER.
And if you were, it certainly wouldn't be 3 - single-spec players would then be forced to take NINE unwanted abilities. That's almost half your levels!
