Matriarch of Desolation is an angelic step, and the first thing the canon reports about it: advancing here makes the bearer a woman regardless of their original sex.
She holds the shares of four authorities at once — Earth, Desolation, Harvest, and Life. The juxtaposition is telling: one and the same power yields a harvest and turns the land into wasteland, and at this step both sides finally converge in one pair of hands.
The advancement ritual is the most literal on the entire path and, perhaps, in all of mysticism: to conceive, give birth to, and raise an entire race.
Its composition matches: the reproductive organs of the Child of Harvest or the heart of the Daughter of Desolation, ten thousand souls of beings who died of hunger, and the remains of an emptied oasis turned into desert.
Ten thousand who died of hunger alongside the birth of a new race — that is the path of the Mother in its ultimate expression: here life and desolation are not opposites but two ends of one and the same thing.