Ancestral Magic is a massively powerful form of witchcraft that draws energy from dead ancestors. Witches are then able to use their ancestor's strength in the way they want. This magic is limited to a certain area such as the burial grounds or the tomb where the ancestors died or were buried. This means if user left the are, they would be rendered without the magic. Ancestral Magic is only open for use of the descendants, hence the name, and needs some blood from the descendants to invoke the spirits. However, some, such as Matthew Evans, have founds ways to use Ancestral Magic without being a descendant of those who have died.
This magic is dangerous because you are using the energy of hundreds of witches at once. When used, fires and strong winds were started because of all the energy. If misused, the ancestors can cut off the energy flow, but this may not happen fast enough, as each one of them must pull back their power.
A downside to Ancestral Magic is that connection with the dead is exhausting and if held for too long, can kill the user. Also, the burial grounds may be hard to locate as you must find the bones and ashes, not simply the graves.
The strongest Ancestral Magic in Meadow Wood is located at the burial grounds of all the dead Bonum Members, which was unknown until Matthew located. They previously thought they were scattered around at different graves, tombs, cemeteries, etc.
The spell to channel Ancestral Magic is entitled "Invocare Spiritus", which means "to invoke the spirits".