Farsight, can you offer further guidance on this spawn for a solo sampire? The fact that you think its easy is leading me to believe i'm doing something very wrong.
Neira, step by step:
1. Pick your targets. Spell casters have priority. If you are under attack by 12 mummies and one bone mage, kill the bone mage, even if it's at the other side of the screen.
2. Hit and run. You can usually kill a magic using undead creature with one hit. The problem is that there are many magic using creatures on screen at once. The solution to that is hitting one, and running away, preferrably to another area where you can hit a spellcaster who hasn't targetted you yet. If you're very quick with honor, you can go on like this with minimal healing. Otherwise, you'd need some form of healing on your template for when you're running away.
3. Save the melee creatures for until there are no other magic creatures within 2 seconds run. The problem with mummies and bone knights is that they take 3 hits to kill. Since you're already wasting time running around like the proverbial headless chicken, that extra 2.5 seconds per kill can be costly. Wait until you have a group where you can stand in the middle and whirlwind/momentum strike away.
4. Take your time, but don't waste it. You may lose a candle by setting the stage for easier kills, but you can make it up in a hurry. The only hard part is starting a level, so once you get it going, there is no problems at all.
5. Conjurer's trinket + EoO = max damage. If you have an undead slayer weapon, then you don't need EoO. I don't have a good undead slayer sword (or necromancy, for that matter, I heal with bandages right now), so I use my best axe (executioner's axe, SSI, ML, SL) and cast EoO for whatever I'm swinging at. As long as I can keep the spawn separated, being hit for double damage isn't a huge problem until Niera herself. And then only if she summons a rotting corpse.
I can't think of anything else right now except for the fact that I wouldn't dream of attempting it without liberal use of orange petals and potions. (no necromancy, I need the petals, I also use a katana or bokuto for when I need to drink a potion)