Dalamar, it might be more helpful if you told us levels and gear of other party members. After all, they're helping you fight Lavok too.
Lavok knows Spell Turning, Mislead, Spell Shield, Spell Immunity, a host of high-level save-or-die spells, and Power Word: Stun. I hope Edwin knows Breach or Dispel Magic or Remove Magic or Secret Word or Spell Thrust, because you have to shave off Lavok's protections in order to damage him, especially that annoying Mislead of his.
As for Lavok's damage spells, keep summons in his face and let the rest of your party damage him from afar. Unless you've installed a mod, Lavok's going to attack whatever's closest to him.
You could also reload from a save before you entered the Planar Sphere and come back when your party has more levels. (Tip of the day: whenever someone gives you a quest, you have a near-unlimited amount of time in which to complete that quest
unless there's a specific time limit on it, as in "meet me here in one hour" means you'd better be there in one hour or else.
)
(I could also say something about how half the posts on this thread left me thinking "now how could this be of any use to him in his current situation?!" But I'll chalk it up to grouchiness and go to bed. [img]tongue.gif[/img] )