I admit, the only oMage book I have read is M20, which you've mentioned as being mechanically flawed. However, it does mention a ruling on HAB/HOO in favor of HAB, saying
Yeah, fuck M20. It's one man's very
particular paen to a certain subset of 2e (unlike W20 and V20 which are actual legit attempts to make an 'Ultimate edition') and thus as someone who got started with Revised I don't spare it the time of day.
When the person writing it was so "Oh, I'm settling arguments" as to waste all that space on his utterly dreadful "this is why turning a vampire into a lawnchair is a bad idea" spiel which any competent editor should have removed, the fact that he also tried to settle in favour of HAP doesn't actually increase my respect at all.
Especially when the funniest thing - as I see it - is that the more Revised-era viewpoint I favour means you
don't need the Technocracy to be as strong. Which is far more gameable. Because the masquerade is far more self-enforcing and the real power lies in the hands of Sleepers, the Technocracy doesn't need to be around every corner, waiting to jump on you. You don't need an omnipresent police state to stop you from changing everything right now, because the real war is the war for the opinions of mankind - and thus you don't have to rely on bullshit conspiracies to justify why it's a hidden magic setting as heavily, which means that your mages actually
can use magic more if they're smart about it and get used to hiding their magic in valid explanations.
That fact that it means that mages damn well
should use their 1-dot spheres to be infowar gods to find out all the exploitable things in their local environment if they want to play well is only a plus from my PoV. It's lazy to just say "Oh, it was a gas main" when there wasn't one. But luring the HITMark down into the utilities closet you splashed water all over the floor of, so you can introduce it to Mr Electricity... well, that's something I'm much more in favour of. And sure, your nordic Verbena might be calling on Thor to introduce this walking machine to tamed lightning, but since you put the effort in to making an electrocution hazard and then used Thor to shape how the zapping happens, you can get away with it.
Wouldn't that imply that as long as a bystander would believe you really did blow up a gas main, its coincidental even if there wasn't one there? I.e. I shoot at a cluster of pipes in a warehouse . While they just contain steam and cables, an average bystander wouldn't know that none of them were gas pipes, so calling on Gabriel to cause a fireball while doing so would be coincidental. On the other hand, if someone present did know what the pipes were for, the effect would be vulgar as fuck, since I'm creating a fireball out of nothing.
Alternatively, am I mistaking your argument, and you're saying that doing so SHOULD be vulgar-without-witnesses, and what the book states is harmful/detrimental to the gameline?
Okay, ignoring M20 entirely (as is fit and proper), this is what I consider to be the process of a player deciding to use an effect:
1. The player decides what they mechanically want to do. This is a purely OOC judgement, with no IC logic. What they want to do is not "throw a fireball", what they want to do is "inflict damage on the enemy".
2. The player checks their spheres and sees if they can do what they want to do. Again - and this is a big divergence from certain modes of play - this is also entirely OOC. Unless you are a Hermetic, the spheres
are a purely OOC concept. The spheres are mechanics, not an in game thing, used to basically balance things and let the GM arbitrate things without turning it into a slapfight. The fact that they resemble the Hermetic paradigm spheres is an unfortunate thing, but unless you're a Hermetic, your character shouldn't be thinking in terms of spheres.
3. You devise your paradigmic explanation for what you're doing. Without a paradigmic explanation, you can't do it. At all. Because your paradigm is where your power really comes from - your spheres are just an OOC way of setting hard limits on what your paradigm can do. This mode of decision making is therefore flexible about the spheres, as
@MJ12 Commando mentioned a while back; variant spheres like Primal Utility, Dimensional Science, the Death sphere I wrote a bit back... they're common, and even when they're not a formal alt-sphere, some people's spheres might have things moved around. Or, like the various Correspondence variants, use a different sympathy relationship.
So you need an explanation for what you're doing. Your Chorister (or your Hermetic, because Hermeticism has a loooooooong history of this kind of thing) invokes angels, your Verbena sheds her blood and calls the sun's warmth down to earth, your Virtual Adept casts (Hostile) hitMark.transferEnergy(Long kilojoules, Object energySource), and your Technocrat simply
loads an incendiary round.
From a practical, in-character PoV, these people are all doing completely separate things. The Traditions hold as doctrine that they're all fundamentally the same thing, but it's doctrine - you don't really
grasp it until high Arete. Maybe the Hermetic tells the Verbena that they're
actually just invoking angels via their crude and inefficient prayer, and the Verbena calls them an arrogant asshole, but they can sort of get into a similar reference frame for a ritual if they want to do one together. And the Verbena can get over the fact that the Hermetic is an arrogant asshole (but I present a tautology).
4. The next step is purely optional, and it's the "How am I hiding what I'm doing to the Consensus?". In the case of some people's paradigms, like most NWO Operatives, they don't actually do this step because their paradigms are so in line with the Consensus that they basically never have to worry about it - and on the occasions they're given non-Consensual foci as Requisitions, their orders to "keep it secret" do the rest. Not everyone else is so fortunate. If you don't feel like hiding it, perhaps because you're a Taftani, then you just skip this step too. And then probably get slapped around the face by Paradox for your pains. And they will be painful.
So, everyone else has to find a way to find a near-Consensual justification for what they're doing, which will hide their stage 3 explanation. This is
not replacing their Stage 3 explanation. And this means they have to play in the Consensus' ballpit and meet it half way. When the Chorister invokes the angel Gabriel to make a fireball, they look for an explanation. And oh, look, there's a gas main here. Okay, Consensus - they metaphorically say - how about the angel Gabriel only makes a small spark, and then that sets off the gas main and that explodes. That's not a very big change, eh, Consensus? You can basically ignore the angel being involved, since
most of the explosion was the exploding gas. Maybe an angel set it off. Or maybe the fact that there's a killer death robot shooting bullets all over the place set it off. Who can say for sure, eh? And then the Consensus nods thoughtfully, and says they'll buy that. And there's a gas mains explosion and the HITMark is consumed in a fireball and the Chorister doesn't take any Paradox. If people are watching and get suspicious, it might be pushed to being improbable.
Now, the problem arises when there isn't actually a gas mains. Because when there isn't a gas mains, an explosion is still manifesting from raw angelic fury, without any explosive gas actually being present. This is a small hiccup, because it means they haven't actually cloaked their magic in a Consensual justification and have in fact just smote the unrighteous. And while this is a righteous thing to do, sadly the Consensus isn't prepared to cut them a break just based on the righteousness of their cause. If they'd thought ahead, they could have brought a pipe bomb with them, and wrapped it in handwritten prayers so it is imbued with the holy fury of Gabriel and brings his vengeance (what they are doing - channelling the force of the angel; what they are selling the Consensus on - look, a really exploding pipe bomb), but alas, no pipe bombs. Well, maybe they can invoke him to unleash the terrible energies trapped in the HITMark's plasma gun, making it blow up due to a magnetic coil fluctuation which releases the energy...
Etc, etc. I think my point stands. Where I separate from the most lax versions of HAP which M20 and a lot of 2e stuff prefers is that your Consensual explanation
has to be valid. If you could have had the gun in your pocket all along, you better not have been patted down and a Sleeper collapsed your "maybe I had a gun in my pocket" field. If you justify the explosion with a gas mains explosion, there actually better have been a gas mains running through the wall. If your blows are actually being guided by your hungry man-eating blade, but you tell people "Oh, I do kendo and know how to use a blade", then if you don't know how to use a weapon the Consensus will get suspicious (although not as suspicious as it'll get when your sword eats someone, boots and all, and then licks its lips).
(I sometimes call this HMLOP - Hypothetical Myopic Lazy Omniscient Perceiver. He's omniscient, but his vision isn't great if a Sleeper isn't watching directly so he misses smaller details and if he's given an explanation which makes sense, he'll let it pass. It's basically a representation of a smeared-out "Consensus" field made up of the sum of the beliefs of all the Sleepers in the area, saturating the area.)