Gorgorath
Undead Dragon of Wrath
Gorgorath is an undead dragon with a fierce temper and a talent for bargaining. She says Evil Eye Grim stole her Jewel of the Undying and offers the Hero a truce in return for helping recover it. After regaining the jewel, she leaves without harming the party, as promised. She regards their return as betrayal; after the Hero reveals and breaks the jewel, she threatens to kill them without it. The Hero, Artix and Galanoth unite to defeat her.
Sources
AQW Wiki: Gorgorath · AQW Wiki: Artix's Quests · AQW Wiki: Galanoth's Quests · A Terrible Mistake · You Mean THIS Jewel? · No Longer Immortal