My friend is a cryomancer and is arguing using Discipline to aim Guns, is this possible? Maybe as a stunt or something. It would be like the inverse of using Guns to aim an enchanted item effect instead of Discipline.
I would argue that this falls perfectly under the application of stunts - using one skill in place of another. From Your Story p.147:
The first possible use for a stunt is to broaden a skill by giving it a new trapping. Often this is a trapping that’s “transplanted” from one skill to another. Sometimes this trapping may need to be modified, or made more circumstantial, in order to fit its new skill.
But the question I still have is, what is the fictional justification for this? Why should someone with the ability to hold together complex mental constructs be better at putting a bullet in a particular place? The price of a stunt (refresh) I think is a fair price for this ability, especially if it is in constrained circumstances:
- Can use Discipline to fire a gun when... or
- has another stunt (or two) as prerequisites Disciplined Shooter allows the character to fire a gun with Discipline, requires Steady on the Draw...
This is all provided a good answer to the above question can be worked out. Remember that Fate mechanics provide support for the fiction, not the other way around.
You use the guns skill to use guns, its just that simple. Sounds like your friend/player is trying to get you to houserule something to make his character more powerful. Even using an aspect to do this would be too powerful and potentially game breaking.
Discipline the skill does not mean trigger-discipline. Its a representation of your character's mental discipline, whereas Guns is a representation of the mental and physical skill in firing and maintaining firearms.
Magic users in Dresden Files have access to incredibly powerful abilities, but that is offset by their low refresh and their tendency to not have as many skills as highly trained (and stunts) as a pure mortal would. At best I think he could give himself +2 to guns with a stunt that had some pre-req and flavor-wise matched his character.
This is what spells are for!
One of the fundamental purposes of spells in DFRPG is to let you use your casting skills in place of any other more mundane skill, at the cost of time and stress. So while a mortal detective can only investigate a crime scene effectively if he's got ranks in the right skills, a wizard can investigate that crime scene just as effectively--if not more so--but it'll take him time to set up the ritual and cost him stress to cast it.
So a character could create a spell which lets him "aim the gun with zen-like focus" or whatever the player's justification is (I'm having a hard time seeing how a cryomancer can justify this). But it's a spell, with all the complications and costs that entails. Perhaps it'll be one of the rotes he learns.
There is only one circumstance I can see Discipline being used to help with a firearm, and that's by using the Combining Skills rule from YS127. This implies that the character is distracted or otherwise in a situation where his focus might wander. While I did look at the Temporary Aspects for things like Lying in Wait or Across my Sights where a character waiting an extended period of time to snipe might need Discipline to stay in place, it quite clearly became more of a Combined roll. The character would need Discipline to help/hinder their roll to stay perfectly still and trained on a target.
Otherwise this seems like a power gaming attempt with the little information about the situation in the question, and should not be done