Witches are a form of natural ally, and they form non-capital SidesErf-b1-p079a.
They may ally with Capital Sides. If they are allied with a side, Elves and Marbits will not ally with that side.LIAB Prologue 24
Their name suggests that they have natural casting ability, similar to Archons.
Sand Witches and Man Witches may be units of this Side.