In
Advanced Dungeons and Dragons, beginning with the First Edition's
Monster
Manual II, an alu-demon is a female half-fiend. Designed as a counterpart to
the
cambion, the alu-demon is said to be the offspring of a mortal male and a
succubus or other female
demon (
tanar'ri). While this does not accord with
the tradition folklore of
incubi and
succubi, it does provide yet another
monster with an appearance superficially like that of a beautiful woman.
Specifically, alu-demons are described as appearing essentially like attractive
human or half-elven females, but with a pair of vestigial bat-like wings
(readily concealed beneath a long cloak). As with
cambions, this description
is not constant.
In the 'tidier' Second Edition, alu-demons were known as
alu-fiends. Third
Edition groups them all together under the heading 'half-demon'. In
Planescape, they might arguably have been regarded as
tieflings, but the new
edition seems to suggest that a tiefling is
less than half a demon.