Can a vampire mage cast spells while in mist form?

I wouldnt have thought so no, they have no eyes for a LOS lock. Although possibly envelop someone within their mist and cast a touch version. Although I'm still going to go down the route of proberbly no

Based on nothing but my gut at the moment (haven't done much in the way of research, honestly, since it's never actually come up in any of my games), I'm going to say "No." I can't think of any examples of it happening in game canon, and off the top of my head I can't think of any examples in vampire fiction in general.

If you want, I can poke around a little and come up with something more definitive for my opinion, but I'd go with "No" for the time being, if it were my game.

Nothing about the power says they lose their ability to see (which would make moving while a mist pretty difficult in and of itself), so by the rules, they sure could. I doubt any sane GM would allow it though.

I vaguely remember this being impossible in previous editions, but so long as they activate astral sight, I cannot think f any reason why current rules should disallow it.

I go with 'no' on a game balance ticket too, though, and because that would raise all sorts of other questions, like, how much of the mist form would have to be in one room to see there and fire up the spell. And before long you'd have several house rules and a character that is very hard to reign in.

I agree. Just for game balance alone, I personally would have any vamp mage in mist form be limited. Perhaps his incorporeal body is unable to channel the mana needed to toss anything more than "mist and move"? In the vampire fiction that I have read/watched, when it was used, mist form is almost always used to either sneak into or escape from someplace.

You can do what our group does. Anytime one of my players or me has an idea they want to try for a character, we playtest it. Run it through some small scenarios to see how it handles. I am a firm believer that canon is okay, but if you want to expand your own game world you are free (and often encouraged) to do so.