Vampiric Mist

Vampiric Mists are monsters with the ability to level drain. They might be found in the subquest Find and Destroy the Cult of the Unseeing. Two are members of the guardians of the first pool in the Throne of Bhaal in Chapter 10. They can move very fast, as if they have permanent Haste on. However, it seems that Vampiric Mists' attacks count as normal or +1 weapons, because they cannot hit a character who is immune to normal and/or +1 weapons.