After killing the witch Radeka, if you go to talk to the dragon (after agreeing to save the dragon from her) the dialog does not give you an option to tell Slane that you have killed Radeka. This means, I cannot do anything to help Slane the Winter Dragon anymore because the witch is dead. This is most unfortunate, because the only way to get xp from this part of the story would be to kill him. Personally, I believe this is a bug and should be fixed.