[Velusion]

Solar Brilliance (Ench 7) is the single best spell to use against hordes of Undead (save Undead Mastery). IF you are playing against the AI it should wipe them out provided your meat shield can hold. Even in MP it can be crippling if the other player hasn't been getting ready for it.

Get a communion up (with astral boosters) and use it. It shouldn't really take that many pearls away from your hording.