They came from nowhere. They were the ordinary necromancers. They inaugurated the age of necromancy, and they were armed only with Ouija boards. They understood the science of Ouija, and with that knowledge they knew they could change the world.
To know how to contact the dead, you need to know where they are. You need to know what a soul is and how it relates to and interacts with a physical body. You need to understand the bicameral brain and the mystery of the "second mind" and second consciousness. You need to know what the true "ether" is and how it connects all of us. The "ether" is non-local, immaterial and dimensionless. It's a mental Singularity, made of light, which is outside space and time and links everything.
Come and learn the secrets of the dead. Discover their language. Make contact with the Other World. You will never be the same again.