2 Armed Mahakala

Two armed Mahakala is also known as two-armed Bernakchen is an emanation of Samantabhadra.

He is not the main protector of Karma Kagyu, but rather that of the Karmapas.

specifically, although there is nothing that says the rest of us cannot also practice on him; the Sakyapa has the two-armed Panjaranatha Mahakala, who is an emanation of Manjushri and holds the rod that emanates many Mahakalas.