Rawgrim wrote...
I meant in combat, only. You have a party member your enemies can`t see. And he can pretty much just walk up to them and kill them in a single stroke.
And that'd be an advantage, to be sure, but I don't think it'd be as useful as you say. You probably wouldn't, for instance, be able to send Cole to a stronghold to murder everyone inside, and (I assume) against bosses his invisibility wouldn't be as big of a deal.
Also, though it's all conjecture at this point, it's feasible (as other posters have pointed out) that Cole isn't the same Cole as we saw during the course of the book. Who knows how he's changed since discovering his identity?
Anyway, I'm not trying to tell you what will or won't be immersion breaking for you. Just that my personal opinion is that I think it's possbile to make Cole a companion without making it totally unbelievable.