There's a trick to break her webbing so that you wouldn't need to waste time/mana casting the images, with the trick you're only webbed for 1.5s, so she can only hit you at most 1 or 2 times.
Even with only 35 DCI (I refined for all 75s as Elf) she doesn't hit that often. If you don't use images, then you can ride an armored swamp dragon (20% damage reduction).
You might also like to try using a 100% HLL weapon, and stone off the 99 necro, drop resist to 119 and then run 100 anat for bunch more damage per hit. You'll should have no problem keeping up with leeching enough mana and HP in this case. <Note: as always, when the RNG decides to F you, you will promptly, and without mitigation, become F'd>