FREQUENCY: Very rare ([Cold Civilized Mountains], [Cold Civilized Forest])
FREQUENCY: Very rare ([Temperate Civilized Mountains], [Temperate Civilized Forest])
FREQUENCY: Very rare ([Tropical Civilized Mountains], [Tropical Civilized Forest])
FREQUENCY: Very rare ([Dungeon Level VI])

NO. APPEARING: 1
ARMOR CLASS: 9, 5, or 1 (see below)
MOVE: 12" (but see below)
HIT DICE: 7+3
% IN LAIR: Nil
TREASURE TYPE: Nil
NO. OF ATTACKS: 3
DAMAGE/ATTACK: 1-8/1-6/16
SPECIAL ATTACKS: [SB]
SPECIAL DEFENSES: [SB]
MAGIC RESISTANCE: [SB]
INTELLIGENCE: Very high
ALIGNMENT: Chaotic evil
SIZE: M
LEVEL/X.P. VALUE: VI | 825 + 10

This foul creature of dark will from the Lower Planes is the essence of
a demon imprisoned in the form of a shadow, which it exactly
resembles. Like the shadow, the creature cannot be detected <e>
90% of the time, since it appears as a vague shape and can easily be
confused, in the guttering light conditions of a dungeon, with the
shadows of dungeon features or of adventurers themselves. It is not,
however, from the Negative Material Plane and so its attacks do not
drain the strength of a victim, as do those of t.he shadow. Instead,
it attacks normally with two claws (1-6 hit points of damage each)
and a vicious bite for 1-8 HP of damage.

The body structure of the creature is most peculiar and leads to the
creature being more powerful in darkness and more vulnerable in
conditions of bright light.

Thus, in daylight or its equivalent, the shadow demon is AC9 and
sustains double damage from all attacks. In torchlight it is AC5 and
suffers normal damage from attacks; in these conditions it attacks
at +I hit probability. In darkness or neardarkness it is AC1, attacks
at +2 hit probability and suffers only half normal damage from
attacks.

The creature is totally immune to fire, cold and lightning, of the
ordinary or magical kinds. However if a light spell is cast upon it,
the shadow demon is affected as if by a fireball (so a light spell
cast by a 5th level magic-user would do 5-30 hit points of damage to
it, whatever the illumination conditions at the time).

Though in normal circumstances (only 50% chance wen if the
creature is seen) they will not be discerned, the creature has small
wings - too small to give it flying abilities, but large enough to boost
the creature's leap in i t s initial attack to a distance up to 30'.
Following this initial leap, it will attack with all four of i t s claws (for
1-6 hit points of damage each), though not with its bite. It will
always leap to the attack if it has not been detected by its potential
victims. The wings also give it the ability to half-fly, half-run, at 18'
movement rate one melee round in wery ten - it will usually use this
manoeuvre as a prelude to escape if necessary.
 

by Neville White