A ghostly hunter

This is a ghostly Di'zok that wanders around Dragon Drool Lake, occasionally venturing near The Crypt Grounds. You can press H to hail him, and he will rotate through four different speech options:

"Venril! I will see you gone from this world! May your torment be a thousand times what mine has been!"

"Kirkata... my love... I am sorry."

"Love that would last an eternity binds me to this world. My punishment."

"What have I done... what have I done..."

Based on these statements, it is safe to assume that this is the ghost of Orthiss, from Orthiss and Kirkata. This is supported by the information we are given about Orthiss's fate at the end of the book.