Infiltration trapping in Burglary

Question

I am translating certain portions of the rules of The Dresden Files RPG to my native language (because there is no official translation), and I fail to understand what exactly the Infiltration trapping does.

You can invoke known aspects on the scene.

Does it mean that I can invoke such aspect without paying a Fate point? Or does it just remind me that I can invoke aspects... like in any other situation?

you can use your Burglary skill to complement (page 214) any skills you use on targets you’ve had a chance to study and prepare for. Thus, Burglary may complement your Stealth [...]

So I can see two situations here. Let's assume there is a camera with a Blind Zone aspect:

1. If I have learned about this aspect by Casing, I can use Burglary to improve my Stealth roll by +1.
2. If I have learned about this aspect by any other means (someone told me about it?), I can't use burglary to improve my roll.

Answer 1

The Infiltration trapping has two separate sets of text; you've correctly identified both, but let's examine both separately.

Given an opportunity to case an intended target... you can invoke known aspects on the scene.

So you use Casing to create / discover an aspect, then Infiltration to use it. The first time you do this would be free, under the usual rules for a free tag of a newly revealed aspect. (Remember, Casing is a type of assessment, so it's immune to the usual time limit for free tags - you can survey the scene well in advance, then tag it when you need to.)

So yes, this is just like tagging aspects in every other situation. The first two sentences are really reminding you of a benefit you already got with Casing.

You can use your Burglary skill to complement any skills you use on targets you've had a chance to study and prepare for.

Note that "complement" means that the skill can only increase, not reduce, your skill (see YS p214). So you'll get a +1 bonus to your other skill if Burglary is higher.

Now we can go back to your example:

Let's assume there is a camera with a Blind Zone aspect.

• If you have learned about this aspect by Casing, then Burglary complements Stealth. So if your Burglary is better than your Stealth, you get to improve your Stealth roll by +1.

• If you have learned about this aspect by any other means that didn't give you any preparation time (such as "someone told you about it"), you can't use Burglary to improve your Stealth roll, because you haven't had a chance to "study or prepare for" the target. If there has been a chance to prepare - someone told you days in advance, and you've studied it yourself - then you'd probably still get the +1 bonus.

(If your Burglary is worse than your Stealth, then no bonus is possible either way.)

• Besides this possible +1 from Burglary, you may also tag Blind Zone as usual. If you discovered it yourself with Casing, that means the first tag will be free.

So the bonus ranges ranges from nothing (if someone just told you about the camera) to +3 (if you Case it yourself, and your Burglary is higher than you Stealth, and you use your free tag.)

Answer 2

In addition to what Tynam says in his excellent answer, there's another (perhaps more important) reason for the existence of the text, rather than just a reminder.

Some of what appears in the text makes little sense why it is being said if taken by itself. But with other parts of the system, taken in whole, they begin to crystallize into a more useful picture.

One of the parts of the Casing trapping description that is very useful in understanding the Infiltration trapping is the reference to the Declaring Minor Details trapping for Scholarship (YW141).

The complication defined in the case of the Casing roll being incorrect makes the user of the Infiltration trapping subject to that detriment- even if they were not the character that cased the location.

In addition, if the Infiltration and/or Casing trappings are transplanted (YW147) to other skills, the relationship between the trappings still remain, i.e if the GM places a limitation on the use of the aspect defined by Casing that it would have to be utilized/justified by the use of Infiltration (i.e. because the details of the aspect require technical knowledge provided by the burglary skill), then these relationships remain.