FREQUENCY: Very rare (at best)
FREQUENCY: Very rare ([Dungeon Level III])

NO. APPEARING: 1
ARMOR CLASS: 5 (see below)
MOVE: 6" (see below)
HIT DICE: 5 (see below)
% IN LAIR: 10%
TREASURE TYPE: Nil
NO. OF ATTACKS: 2
DAMAGE/ATTACK: 1-4/1-4
SPECIAL ATTACKS: Nil
SPECIAL DEFENSES: See below
MAGIC RESISTANCE: Standard
INTELLIGENCE: Animal
ALIGNMENT: Neutral
SIZE: M <(about 4' high && 2' avg. diameter)>
LEVEL/X.P. VALUE: III | 130 + 5

The natural form of this beast is a grey-green lumpy cylinder about 4'
high and 2' average diameter. A short single leg trails behind the main
body and has a suction cup like that of a snail. Other similar suction
cups under the main body itself permit the beast a jerky mode of
locomotion. Two 5' long tentacles emerge from the top of the body
but there are no apparent eyes, ears or other features - indeed the
whole creature is a constantly changing mass of a rubbery, dough-like
substance the same colour as bilious human flesh.

The creature will not normally attack unless threatened, but when it
does so it strikes with its tentacles for 1-4 hit points of damage each.
When engaged in melee the creature exhibits a startling power of
irnorphisrn. At the beginning of each melee round (except the first) it
changes its hit dice and armour class by 1 point each towards the
values of its opponent, at the same time gradually changing its shape
to resemble its opponent's shape. When hit dice and armour class (and
hence appearance) are the same as those of its opponent, the creature
instantly alters its attack and movement to fit the subject.

Note that the imorph assumes only the physical appearance of i t s
opponent; though it will grow various appendages to copy i t s
opponent's weapons and limbs, it will still strike with the equivalent
of two tentacles each round for 1-4 hit points of damage each (even
though one tentacle may look like an arm wielding a sword and the
other an arm holding a shield, for example). The hit points of the
imorph remain the same even when the hit dice value changes.
However, the creature will change its hit probability to conform to'its
new hit dice value.

When the imorph is exactly the same shape as its opponent, has the
same hit dice and the same armour class, it changes to the appropriate
attack matrix for its hit probability (the fighter table, for example if
it is attacking a human fighting man). It remaihs attacking on that
table until it starts to change back again towards its original form.
When the melee is over, or when the imorph is down to 8 hits or
fewer, it will revert to its original form by the reverse process,
changing armour class and hit dice by 1 point each per melee round.
If faced with more than one attacker, the imorph will select one at
random to attack and to emulate. If the original 'model' dies during
melee, or retreats, the imorph will immediately start to alter in order
to emulate another opponent.

Within the creature's body there is a small organ, corresponding to the
human liver, made of a rubbery green substance. Within the organ is a
liquid of similar colour which, when mixed with water in equal
quantity, serves as a potion of polymorph self. There will be sufficient
liquid in a single imorph to make 1-3 draughts of such a potion, and
it is for this reason that the imorph is attacked by adventurers.
 

by Andrew Key