but I'm curious if the power level of, say, Evocation is in part dependent on the fact that you're not allowed to kill people.
Hello
This is a bit of a tangent, but I feel it's an important question on the "feel" of the system.
In some systems (let's say, many editions of D&D for example), some attacks are too weak to kill a foe, period. For example, if you threw a dagger, and you're not particularly good at it, at a tough dwarven warrior, this will not kill him, period. You may hurt him, you will certainly anger him, but he has too many hp, that even with a critical hit, he won't die from it.
In some other systems - and in real life! - even a somewhat weak attack has the potential to kill. There was a court case in Ottawa a few years back where someone sucker punched someone else, and the single blow ruptured a blood vessel in the victim's brain, and he died on the spot. That is perhaps an extreme example, but say if I shot at someone with a weak gun, like say a .22, I would still be charged with attempted murder - even though it' s a "weak bullet", it can still kill. In warhammer frpg 2nd ed, each attack has the potential of having its damage "explode", so an arrow from a puny goblin has a small, but not negligible, chance of slaying a mighty armored knight.
This is a pretty important question. If you do it D&D style, the PCs can feel more heroic... but sometimes to the point where it is very plot disruptive. It can lead to "so what the bad guy is pointing his gun at me and telling me to freeze, I can take the damage!" kind of thinking. If you use a more realistic system, it can lead to more realistic roleplaying - if someone is shooting at you, it's *bad*, no matter how tough you are. On the other hand, the adventure can be derailed by an important NPC (or PC) being killed by a rock thrown by some puny goblin punk.
So... how does this work in Fate 3.0? To get back to the topic at hand, if we are closer to option two, it means that you can't really ever throw aggressive evocations (say, like beams of fire) at other humans because you risk killing them - in other words, you can't use it to soften them up - not without risking breaking the laws of magic.