The head of the coven, a ruthless Night Hag. Escaped the coven when the party killed her two sisters, vowing to return to get them some day.
After returning to her original lair, the group confronted her, and managed to finish her off, ending the corruption for good, or so they thought.
Hala remained, at least her spirit did, and got connected with Vuthul, granting her strength to try to finish what she started, but she was stopped by the flock once more, who sundered her spirit once and for all.