A shadowbinder is a practitioner of magic who binds shadows to do their will. They possibly originate from Asshai, as the shadowbinders Melisandre and Quaithe come from the city near the Shadow Lands.
A Game of Thrones
A Clash of Kings
Stannis Baratheon enlists the aid of the red priestess and shadowbinder Melisandre, who claims that shadows are the servants of light. She gives birth to shadow assassins that kill Renly Baratheon and Cortnay Penrose.