There are two things to consider:
- What the White Council considers breaking the laws and
- What the rules consider breaking the law towards the Lawbreaker 'Power'
YS182.
This view is enforced in the text on YS232, i.e.
You could say that the Laws exist as two separate concepts with 99%
overlap—the Wardens of the White Council enforce one concept (law),
while reality metaphysically enforces the other (nature).
The first one is pretty well set out in terms of targets on YS232, i.e.
The White Council has made clear that their Laws don’t apply to
entities that aren’t people. The Laws of Magic are strongly oriented
on protecting the lives and rights of mortals. Creatures and folks
that the Council might classify as “monsters” are fair game. With
that said, this is a rule of thumb where it’s easy to stumble into the
grey area, with things open to interpretation by the Warden on the
scene—and given that Wardens have a lot of latitude regarding the
whole “judge, jury, and executioner” bit, it’s a grey area that you
want to avoid stepping into as a spellcaster.
This doesn't seem to indicate casters, but in truth, I think it does. It falls into that 'grey area' mentioned in terms of targets, i.e. if it is possible that the Seelie Court (or Sponsor) will step in to take exception to their subject having their head removed from their shoulders and it can be proven to be so (Marked by Power, anyone?), then that will give Wardens pause. Then again, if the Laws of Magic don't apply as a caster- they also don't apply as a target, making the caster a valid target outside of White Council influence under the case of 'aggressive self-defense' or somesuch.
In terms of the second part, it becomes even grayer, but I think it can be solved with a judicious look at aspects. If the changeling has not made the choice, they count as mortal for purposes of the game. The same with Sponsored magic users. So I'd think that the rules part would apply in both of those cases.
Again looking at YS232:
Whenever you choose to break one of the Laws of Magic, you’re crossing
a very real line. By taking such an action, you’ve altered your
self-image and your beliefs—the very basis of you—to be the sort of
person who breaks that Law.
Though this is flavor text, it does point to the view that its based upon what the psyche of the character identifies as - mortal or not.
Now, if the mage is an Emissary of Power because he's explicitly not mortal, that's a different story. A lesser demi-god of some long lost power is decidedly not going to have the same worldview as the mortal emissary of the same.
In general, potions and other enchanted items are like stored evocations, i.e. intended to hold a single, pre-generated effect that is stored until released (YS279).
But what can this effect be?
- As to the point of whether it can replicate a skill, that part I'd say is true.
- As to how long it can last, it can be for an extended period of time.
RAW isn't very clear on this, but the example of magical effects is. Look at (YS304). True Seeing Ointment grants a +6 to alertness checks for an extended period of time. Looking closer at the rulebook, for a potion, you get this blurb: "The effect strength of a potion, like enchanted items, is equal to the wizard’s Lore." (YS280) You can also boost that, by devoting more potion slots, and/or taking a compel.
So within those limitations on the effect level, I'd say that he can.
There's another important bit in play, that I think is worth mentioning.
My current ruling will be: No. (unless somebody can point me to some
source material that more clearly defines the subject)
My Reasoning in addition to what is above: A Stunt (and by extension
Refresh) is useds to add a new trapping to a skill. Essentially
letting the chacter do things with one skill that that normally
couldn't be done with that skill.
I've never ruled on anything in DFRPG. I've talked it over with players, consulted outside interpretation, and discussed rules. But Fate in general is a game where you have to take into account the story that the players and yourself are creating in a coordinated effort.
I'd advise that you be careful with making 'rulings', and instead consult your players and make clarifications and extensions to the world with them.
Best Answer
Yes, it's possible to inflict Mental Stress with magic without breaking the Laws of Magic. You just can't affect someone's mind directly; whenever you're thinking of an effect that could cause Mental stress, the brain is strictly off-limits.
There are plenty of ways to cause Mental Stress with less psychic effects, though. The entire field of illusion (which Spirit magic does just fine) will work; a few well-timed telekinetic effects can help. Like most illusions, it will work best if your target is unfamiliar with magic. In the Dresden Files novels, Molly uses illusions as her main weapon, but it isn't violating any of the Laws of Magic. Here are a few examples:
Just because the target is taking Mental Stress doesn't mean that you've actually invaded their mind; they just need to think that something terrible has happened. Keep in mind, though, that your actions still have to make narrative sense: simply applying a Weapon:3 of "terrific illusions" every combat round might only work the first one or two times it hits an opponent; after that, they may get accustomed enough to it that it doesn't have the same impact. Building up an illusion over multiple rounds with Maneuvers, and then hitting the target just once for Mental Stress, may make more narrative sense.