Witchcraft
Witchcraft can only be taken if the player choses a High Concept or an Aspect for their power.
Overcome: Witchcraft can be used to overcome obstacles, but it tends to be slower and less forceful in most situations. Think how natural forces might overcome an obstacle: like forcing a door because humidity causes it to warp. You could of course imagine a hurricane ripping it off its hinges, but this is a forceful way if no Hurricane is actually present on the scene...The TN serves as the stress needed in the scene, you can lower this amount by sticking close to the time needed for nature to do its work, each scene you wait after setting "Nature" in motion lowers the stress required of the scene by 1, paid on the actual moment when you get to the scene to overcome it. So you could set the door to warp and go do other scenes, and when you come back you can just push it open (after paying the actual cost).
The likelihood of the event naturally happening can also lower the stress, up to a minimum of 1. Getting the floor the weaken so you can fall through when the house is on fire would make it much easier... Or warping a door in a humid derelict building could cost as little as 1 stress.
Create advantage: Witchcraft can be used to create advantages (or disadvantages) in the form of Curses and Charms. The main difference with other skills (and casters) is the highly ritualized form (and time) this takes. Advantages towards persons or creatures require a bit of their body, be it a clip of hair, a nail, a bit of skin, a drop of blood,... while advantages to zones require some form of preparation (sigils painted or daubed on, sacrifices, essences, ...) When done in the witch's house or in a coven, apart from the component cost and time required there's no other cost at all. Components can lower the cost of the charm (or curse), down to a minimum of 1, on a 1 for 1 basis (Acquisition cost to Scene stress).
The great advantage is that it's never immediately apparent that a witch's power was involved, and even if that's surmised, it's even harder to detect or prove (doubling the TN).
Attack:
Defend: