Creatures with the cold blooded blood temperature are unique only in that they are particularly vulnerable to certain cold attacks. They have a 50% chance of being slowed when they are damaged by any of the following cold sources:
They are also more strongly affected by Metabolic Englaciation, remaining slowed for twice as long.
Notably Hydras are cold-blooded monster, so if you don't have a slicing flaming weapon to deal with them, another good strategy is using a non-slicing cold weapon to slow them.
For the late game, [Draconian]s which are populating the Realm of [Zot] are also cold-blooded.
For a list of cold-blooded monsters, see Category:Cold-blooded.