Crypt Winds (Sor/Wiz 3)

   When this spell is cast, a foggy, damp, crawling
mist spreads forth from the caster. The hazy winds spread
from the caster out to a 60ft wide by 25ft tall cloud. This
fog grants all undead within it a +2 deflection bonus to AC
against all attacks upon them while they remain within the
fog. Living creatures within the cloud take 1d4 points of
cold damage each round.

Material Components: a vulture’s feather
and the heart of someone who died from freezing