Enchanted Gun?

[UmbraLux]

Basically, what's the power trade off for adding aspects to the target?

Putting an aspect on someone is resisted / resistible.  They're also removable if the victim takes appropriate action.  Mechanically, you'll have to add enough power to the aspect to account for both resistance and time. 

[wyvern]

Minimum power for an aspect from magic = 3 shifts.  Possibly plus additional shifts for duration - though, as per here, houseruling the default duration to something more than just one exchange is a very plausible houserule.

[UmbraLux]

Minimum power for an aspect from magic = 3 shifts.  Possibly plus additional shifts for duration - though, as per here, houseruling the default duration to something more than just one exchange is a very plausible houserule.

Yeah, while it's not RAW, I like the idea of using the time increments chart* along with a "what makes sense" approach to temporary aspect duration.  In play, most tend to fall in one of four time categories:  fragile / one exchange; until resisted / removed (less than a scene); scene; and consequences.  That said, the changeling PC in my game did pick up a curse which will last years.   

*Roughly what consequences are...temporary aspects around for longer periods of time based on severity / shifts.

[Logiwonk]

Gotcha, so the way to handle a "freeze bullet" would be to treat it as a strength 3 maneuver that lasted for two exchanges or a strength 4 maneuver that lasted for one?

[sinker]

The duration of magic maneuvers is weird. Fred has said that he might give some of those maneuvers a duration of the scene or until removed (much like they suggest similarly bending the rules for veils). But yeah, by RAW you have it right.