Befriended by Talis the White (Kasterel) to escape Skyreach Castle, but then turned opportunistically when Talis realized Rezmir and the Red Wizards were out of the picture.
Talis rode Glazhael in an attack on the castle, eventually instructing him to eat Vyerith - enraging Alorrik, who then dimensioned door to the dragon's back, broke his staff - and delivering the damage needed to incapacitate the dragon, who then fell to his death far far below.
The bodies fell deep into the Underdark, the dragon finally landing upon and pinning a hag of the Coven of the Dark Mirage.
(See: Sky Battle of Giants and Dragons )
(See also: wiki)