Thanks!
As for getting revenge on the PCs, how about framing them for something? With rogues and magic at his disposal, the bad guy should be able to make a pretty convincing set-up. Even better, he could try to infect a couple of them with lycanthropy (people with low fort. saves, such as the spellcasters). Eventually, the party would have the paladins and priests against them as well as the goblins. They may even end up taking shelter in some of the wizard's hideouts.
If the PCs are hated enough, the wizard can use his criminal contacts to find out where they are hiding and turn them in, thus becoming a town hero!