But that takes up precious time which can be used for smacking!

I do have a point with that flippant comment, though... it takes time to set down what rules you are using, what kind of game you are playing, what you will and won't allow. Some of it is based on awareness (if you never run into critters with Regeneration, you may never discuss how you are using it in your campaign), but a lot of it has to do with the amount of free time you have to spend gaming. Some people may have the time to sit down and flesh out everything, but most folks want to "just play" and worry about it later. Especially folks with lots of Real Life timesoakers like job, family, friends, favorite shows, etc.

Our group uses a group listserv so we can hash out some of our discussions on various house rules or interpretations online during the week, so we don't have to waste precious gaming time on those. If something hinky comes up during a game, usually we let the GM (whoever it is for that week) make the call, then discuss it later by e-mail on the listserv. It works pretty well so far.

We also don't use rule zero all that often (i.e. "the GM is always right")... it's really only necessary when there is a discrepancy in the rules and we want to move on. Even after the "rule zero" smacking, every player in the group has an equal say in the rules after the game, mostly because half of our players also rotationally GM. Equality and Democracy works better than Tyranny, in our game. YMMV.

Honestly I like this idea. The great thing is, we already have a substitute spell, one with much better mechanics and fewer odd rule complications that does thematically the same thing: the Camouflage/Physical Camouflage spells. The only reason to even bother with the Invis-type spells at all is that they're trivially better than Camouflage, which is kinda stupid.

Of course Camo needs a bit of work too, as the flat modifier it provides is just as dumb as the automatic Perception failure Invisability provides. How about something like it adds the Force of the spell, plus any net successes (maximum equal to Force), to the TN to spot the mage visually? An analogous mechanic would apply to the Stealth spell, which needs reworking for the exact same reasons. This way it's still quite possible, albeit unlikely, that you'll spot a mage with lots of successes and a high-Force spell, and low-Force spells still provide a tangible benefit, though not quite as wonderful and nearly broken as the low-Force version is currently.

I thought someone would come up with this as an alternative. Shouldn't Phantasm be subject to the same interpretation, thereby solving nothing? They are in the same exact spell subset and work in similar ways.

I think it just made a couple other spells more needed. Camouflage and mask or physical mask. It also makes the critter power concealment that much more needed. IIRC, somewhere it says everyone concealed by the power is aware of each other. Or did that get erratta?

It's actually better than Invisibility, since Trid Phantasm is multi-sense.

I'd say every success reduces the visual penalty for Blind Fire by -1 and increases the Perception test TN by +1, to a maximum of +8 or Force, whichever is higher... the more successes you get, the more the target "fades" from view.
The TN would be the OR of the wall or 4 for living creatures.

It does? Camo gives you a blanket +4 to perception and ranged combat tests, and blends you with your background. This spell is a manipulation that simply turns someone translucent (or transparent, given enough successes).

LOL... yes it would.

One, that spell doesn't exist nor does it work in 3rd edition. Two, even in second edition that spell wouldnt work on enclosed vehicles, only mororcycles.