With a solo mage i managed to take them out with only two things- a fully charged wand of cloudkill and a protection from magic scroll, simple read the scroll and fire away with the wand, you can then lead enemys through the gas to kill them (u will take damage, but nothing a ring of regeneration can fix
)
The only really hard bit is fighting the vamp, so perhaps i should have taken a wand of fire too.
------------------
Those who ph33r the darkness have never seen what the light can do