The Coven

From publisher blurb:

You've made a pact with a coven of witches who have unified their magical might to become an otherworldly power. Using strength in numbers, the coven binds to one another, allowing each witch to share spellcasting abilities, arcane knowledge and possess a shared consciousness. Every coven is different, not necessarily evil, and can be crafted around the player at the DM's discretion. A coven typically consists of at least three members, with thirteen considered the ideal size, allowing for a leadership structure to settle arguments and solve problems. A leader can emerge inside the coven, which can be chosen democratically based on wisdom and respect or naturally with the most powerful leading.