The Sycorax appear to be skinless humanoids wearing mantles of bone, usually keeping their features concealed under helmets. They are proficient in the use of weapons like swords and whips, the latter which can deliver an energy discharge that disintegrates the flesh of its target.
The Sycorax also appear to have technology that is either disguised or treated as magic, referring to "curses" and the Doctor's regenerative abilities as "witchcraft". The Sycorax leader referred to an "armada" that they could use to take Earth by force if their blood control plan failed.
They also appear to have a martial society, with traditions of honorable combat, yet they have no qualms about killing prisoners.