You'll meet Valygar in his cabin in Umar Hills while hunting for him for the Cowled Wizard Tolgerias. When you talk to Valygar, you'll learn that the Cowled Wizards only want him so they can use his blood to enter the Planar Sphere in the Slums District. Valygar will inform you that his ancestor Lavok was in control of the sphere when it disappeared 500 years ago, and that Lavok uses the bodies of his blood relatives to extend his life. So Valygar will want you to ignore the bounty from the Cowled Wizards, and instead go with him to the sphere and end Lavok's life.

Note: Helping Valygar will mean betraying Tolgerias. There isn't any way to work with both of them.

Inside the Planar Sphere, Lavok won't be quite as evil as Valygar made him out to be, but no matter what you decide, Lavok will die at the end. You'll also run into Tolgerias while you're there, and he'll attack you -- and die as well. For more information on these events -- and the other things that you can do while you're inside the sphere -- please refer to the Planar Sphere page. When you eventually complete the sphere, Valygar will offer to continue traveling with you.