Spell, magic item, or creature—what is a Liderc? Foremost, an evil thing born of implausible circumstances; a character of 5th level or above must sleep seven nights hatching the unfertilized egg of a black hen in his or her left armpit. If the egg miraculously survives intact (effectively, 7 successive Wisdom/Luck checks at –2 must be passed), on the seventh morning it will hatch a demonic creature.
A Liderc can take three forms: a black cockerel with red-rimmed eyes; a coal-black wingless imp the size of a cat; or a demon lover of the gender desired, human-like, with an off-key beauty. In all forms it has the stats:
HD: 5+2; AC: 3 ; MV: 6 (flying, fowl form) / 9 (imp form)/12 (human form); AT: damage d4 bite (fowl, imp) or as human; DF: only takes weapon damage from +2 or higher; saves vs. spells at +5, even spells without a save; Mind: average; Reaction –3; Morale +2.
The Liderc can change form and perform blink at will, and can perform invisibility, change self, clairvoyance, and knock up to three times each in any given night. If its form is destroyed in combat, it will dissipate, and reappear by its master’s side the next sundown. A Liderc may have one or two special powers, such as the ability to change into a will-o-wisp form.
While good relations with its master persist, the Liderc will obey his or her every command by night, even erotically. Left to its own devices, the Liderc will nightly steal treasure from the vicinity, stockpiling it for master.
But the Liderc exacts a price; the master’s sleep becomes fitful and oppressive as the Liderc squats on his or her chest, draining life force at 500 xp a night. At zero xp the master is permanently killed, and the Liderc leaves for good, carrying a fresh soul to hell. If relations turn sour, the Liderc finds excuses to refuse the master’s will, while still draining life force nightly.
Born implausibly, the Liderc can only be killed by impossibility. The trick is to have it agree to do a task that it believes to be possible but is actually impossible. Literal-minded, the Liderc will implode on itself in frustration at being unable to complete the task.
And in this case here's what the Liderc left behind:
If counted, there are 9,403 coins stacked into 97 piles, six of which have 96 coins and the rest, 97. This is the final state of the trick by which Arpad III banished his liderc. A better mathematician than the demon, he ordered it to divide the coins into piles of equal number, after determining that the number of coins was prime. Amid the stacks sits all that’s left of the liderc, the original hen’s egg, now blackened. If broken, foul vapors fill the room, with the effects of the stinking cloud spell. All the coins radiate slight evil magic because they received a dying curse from the Liderc. Anyone who takes possession of any part of the treasure and sleeps within 50 feet of it will be plagued by nightmares, will not recover hit points that night, and will lose 100 xp. Zero-level shopkeepers and the like will be found dead in the morning, and there certainly will be questions asked about their dealings the day before (assume that the treasure coins are the first ones spent by the adventurers unless they say otherwise). A remove curse spell will return the treasure to normality.