I won't go into specifics however all you need to do is ask yourself a few questions.

- What are the strengths of the Paladin (particular highlighted in this fight)?: One round attack spells, insane tanking
- What can a necromancer do to eliminate these things almost entirely?: Well no spoon from me but you need to go over every spell and skill a necromancer has and you will find it/them. Maybe thinking outside the box slightly is required.