Crafts is the skill of working with machinery, for good or ill.
The default skill is called Crafts because it’s what we use in the examples, but this skill might vary a great deal depending on the setting and what kind of technology is available. In a modern or sci-fi setting, this might be Engineering or Mechanics instead.
Crafts allows you to build, break, or fix machinery, presuming you have the time and tools you need. Often, actions with Crafts happen as one component of a more complex situation, making it a popular skill for challenges. For example, if you’re just fixing a broken door, neither success nor failure is interesting; you should just succeed and move on. Now, if you’re trying to get your car to start while a pack of werewolves is hunting you…
Create an Advantage:
You can use Crafts to create aspects representing features of a piece of machinery, pointing out useful features or strengths you can use to your advantage (Armor-Plated, Rugged Construction) or a vulnerability for you to exploit (Flaw in the Cross-Beam, Hasty Work).
Creating Crafts advantages can also take the form of quick and dirty sabotage or jury-rigging on mechanical objects in the scene. For example, you might create a Makeshift Pulley to help you get to the platform above you, or throw something into the ballista that’s firing on you to give it a Jammed Pivoting Joint and make it harder to hit you.
You probably won’t use Crafts to attack in a conflict, unless the conflict is specifically about using machinery, like with siege weaponry. GMs and players, talk over the likelihood of this happening in your game if you have someone who is really interested in taking this skill. Usually, weapons you craft are likely to be used with other skills to attack—a guy who makes a sword still needs Fight to wield it well!
As with attacking, Crafts doesn’t defend, unless you’re somehow using it as the skill to control a piece of machinery that you block with.