This object is a translucent, yellow crystal lozenge about six inches
by four inches by two inches Within the crystal is the image of an
octopus or squid with twelve tentacles. Only Clerics and Magic-Users
may be affected by or possess the Eidolon. Any Cleric or M-U viewing
this object for the first time must save vs. magic or fall into a hypnotic
trance lasting 2-8 (2d4) rounds, during which time he will attempt to
take the Eidolon for himself, and to kill anyone attempting to stop
him. If he succeeds in possessing it. another saving throw vs. magic
must be made, or the owner will do everything in his power to reach
the sea and swim with the Eidolon as far out as he can, eventually
drowning himself through exhaustion.
 

If a Cleric or Magic-User is successful in obtaining the Eidolon without killing himself. then he will become aware, through some
telepathic means, of the following powers of the Eidolon:

Summon and Charm (as a 20th-level Magic-User) one of
the following types of monsters, provided the user is within range of the sea:
 

d100	Monster	No.  Appearing
01-10	Killer Whale (15 HD)	1
11-20	Giant Squid	1-3
21-54	Vampire Ixitxachitl (5+5 HD)	1-4
55-100	Giant Octopi	2-5

The Charm of the Eidolon works exactly like the 4th-level M-U spell
Charm Monster with regard to the percent chance of breaking the influence of the Eidolon. What the user of the Eidolon does not know is
that when the monster is freed of the Charm, it will try to destroy the
user! Only the power of a full Wish will negate this effect of the
Eidolon,
 

The range of the Eidolon’s summoning power is the user’s level
multiplied by five miles. The Eidolon wilt function in this manner 2-8
(2d4) times before losing its power, at which time it will dissolve into a
puddle of sea water.

Experience point value: 5,000.
Gold piece sale value: 10,000.