A grave keeper, called Farmiah, roams the terrains of Stonegarden. She is bothered with Ryker's behavior. According to her, the man harms Undead. She asks you to kill Ryker.
Ryker lives in a mansion in Stonegarden. You can find him in his office. You should talk to him. He can give you two quests - The Midnight Oil and A Generous Offer. They are both worth completing especially because A Generous Offer quest ends with Ryker's death. However, if you decided that you want to kill Ryker without completing these quests then you should use Source Vision ability and speak with his servants. Also, if you decide to absorb their energy, Ryker will lose his allies.
In order to complete this quest, you must go back to Farmiah and inform her that Ryker is dead.
Reward: 26900 experience points + 3 guaranteed rewards + 1 from 4 that you can choose from depending on character's class