Avatar: The Untold Legend
The man’s only seen with a black robe, and hides his face with a hood attached to the robe. The right side of his face is scarred from top to the bottom, indicating a terrible burn. His right eye no longer functions, but is in place and shines when light hits it, as if made from glass.
His past story is unknown, but Liu is apparently the member of an organization that is behind the attack on Earth Rumble II, as he was supposed to get a report after the attack. The Six Benders intercepted the report and tried to follow him, but he found out their trick and confronted them. After he took an unexpected blow from Kuzo that burned his face, he tried running away, but was captured and imprisoned beneath Omashu’s palace. He soon escaped from imprisonment though, and was last seen receiving a “reward” from another man(wearing a black robe like him) just outside of Chin Village.
Liu is an extremely powerful earthbender, capable of hurting his enemies even with simple earth blasts. He also has an unknown talent, “bending energy” as he calls it, that allows him to neutralise bending attacks that would normally harm him.