Becquila was a corrupted sorceress, and a member of the Rooks. She was the master of the corrupted Snow Troll, Klutus, and they were both killed at the Ydra Forest. Her sister was also a Rook, who was the master of Stahl and killed at the Rooks' Hideout.
How Becquila Fights
She runs away and leaves white circles and then comes back. When she runs away, she is invisible.