This is my entry for the grand one-page-dungeon contest. Thanks guys for this wonderful idea. Since the contest is closed and Chatty DM encourage everybody to share their entry, I present you...
Terror of the Songhaunt Crypt
Background
Laleth Numandhyr was a celebrated elven bard in the kingdoms of elves and men alike. While he was sometimes described as a little bit overambitious and hard to handle by his hosts, he wrote many significant pieces of art, and was even trying to incorporate his elven magical talent into his music, to create wondrous performances. But all the fame and glory was not enough for Laleth. There was still one thing to be done. He hasn't wrote a symphonies yet that would turn him into an immortal bard. He locked himself away in a secret hideout and began to experiment with his mystical music. Over the time however his compositions became more and more bizarre, while he was exploring spheres of music that were incomprehensible for most of his audience. During one of his rare public appearances the audience started to boo him. In a fit of rage he hurled a terrible necromantic infused cacophony at them, which turned the terrified listeners into undying and pitiful Songhaunts that became his loyal eternal audience. With them he fled the theater to one of his secret hideouts where he jealously guarded all his musical treasury. From this hideout he used his dark bardic powers of performance and persuasion to cause strife and havoc, while he was turning slowly into a creature of vileness. At one point his hideout was discovered by elven agents of good who wished this evil be removed. They sealed his domain and tried to eradicate all memory of Laleth. Now he is cursed to forever exist in an undead state, and blames those who are still alive for his state. Laleth seeks revenge on all philistines who blew his masterplan to become the greatest bard in history - and fortune played him well again.
In his underground tunnels a Destrachen was attracted to Laleth's lair by strange melodies. With his sonic powers the Destrachen shattered a wall that led to Laleth's lair...
Character Hooks
* PC's were actively looking for the crypt to prevent the evil Order of the Lyre from finding Laleth using his powers
* PC's stumble accidentally upon the lair, while hunting the Destrachen in his underground tunnels
* An elven warden approaches the PC's and tells them that the ancient seals that guard a terrible evil have weakened
Dungeon Features
Magically treated masonry walls, flagstone floors, strong wooden doors, unlit unless otherwise specified.
Room Key
These are the lower rooms of Laleth's hideout. Before he was imprisoned there where upper rooms that contained mostly his living areas. These rooms were destroyed and collapsed by the elves before they locked at the lower level. The lower rooms could not be destroyed by the elves because they were magically treated, so they sealed this part of Laleth's hideout and bound the evil bard to this place. He cannot leave this place in his spectral form. However if he finds a host he can posses he is free again.
Map
1. Entrance Hall. This is where the destrachen arrived. The room contains the magically sealed passage to the collapsed upper floors, as well as a magically trapped door to Laleth's chambers. The destrachen triggered a powerful enthrallment spell when it investigated the room. If the destrachen is attacked or otherwise disturbed the spell wears off and it attacks anyone in sight. The room is covered with elven warnings and magical abjuration spells that can be deciphered by PC's with the appropriate skills.
2. Hallway of Remembrance. The walls of this hallway are full with self-aggrandizing paintings of Laleth. One of these paintings shows him playing some actual notes. These notes must be played to open the door to his inner chambers (and the magically sealed door to area 7). It's a relatively easy melody to play. However Laleth often forgot the tune because his mind was so busy composing his next masterpiece. If they PC's try to open the magical locked door without playing the tune, they are instantly attacked by three Songhaunts that emerge from the wall.
3. Music Chamber. In this room the ghost of Laleth's former elven muse Sharlain is trapped in eternal sorrow and woe. Laleth strangulated her in rage with a string of his lute without a reason. Her spirit cannot rest while Laleth still exists. She is sitting on a hapsichord and playing a sad waltz. With her enchanting ghostly female voice, she is crafting beauteous tapestry of sound, while telling the sad tale of her murder (for those who understand elvish). When the PC's enter the room she has turned her back on them, since she don't want anyone to see her facial expression in the moment of her death. She does not give any answers if she is spoken to. She even seems not to notice the PCs at all. However if there is a bard in the party and they leave her in peace, she might appear in the battle against Laleth, aiding the party with her music (providing a moral bonus for combat and save rolls). The hapsichord is already in a bad shape and almost unplayable unless it's repaired. If the PC's search the room they can find a silver ornate tuning fork. In addition the sheet music of the tune she plays lies on the hapsichord. It's a complex masterwork elven tune. If a bard can master it he gets some benefits when playing it (like more money, more reputation, or more girls)
4. Rehearsal Room. This room contains a small stage and a couple of chairs before the stage. Three summoned instruments hover in the air and play a horrible melody, while four Songhaunts sit in front of the stage listening and applauding (silently) to the off tune music. When the PC's enter the room the Songhaunts turn around and attack. While in the room the PC's get a -2 morale penalty to attack rolls and saving throw because of the terrible jingle jangle music that somehow weakens their fighting ability. This effect can be countered by a bard.
5. Garderobe. Behind the stage is a small garderobe. The room contains a large mirror and a dressing table. Always suspicious Laleth stored a magical elven dagger in the table. There is also an enhanted gong here that can store a single spell up to level three. Laleth used the gong to trigger special illusions for his audience.
6. Instrument Storage. This room contains Laleth's collection of mundane musical instruments. The PC's can find a delicate harp, a chime staff, a painted mandoline, a bell chord, a dulcimer and a pair of resonant orcish war drums. All instruments are of masterwork quality. Some of the instruments are unfortunatly defunct, because of broken strings, etc. Two Songhaunts inhabit the room and are stoically trying to maintain the instruments. The Songhaunts attack when the PC's enter the room.
7. Tomb of Laleth. Most of this room is taken up by a octagonal platform. Three steps led up to the platform. The room is lit in an eerie blue fire by a single large brazier in the middle of the platform. Faint ghostly whispers can be heard throughout the tomb. Slowly Laleth the undead revenant of an ancient bard becomes visible. His translucent fingers hold a long, ornately carved flute. His cold lips produce twisted and malevolent sounds of some strange and dreadful enchantment, when four Songhaunts appear out of nowhere and attack while Laleth utters a terrible and blistering curse from the black dephts of his soul. During combat Laleth employs fear invoking sounds, deadly illusions, as well as soul shredding dirges capable of slaying the PC's where they stand. These effects can be countered by a bard. During combat Laleth also tries to possess a PC or NPC with the highest charisma to escape his prision. He tries to kill everybody else.
Encounter: 4 Songhaunts, 1 Spectral Bard
Treasure: Laleth's Magical Flute
8. Treasury. Laleth's magical flute also acts as a key to his treasury. Other attempts to open the hidden door trigger a strong sonic trap. His treasure includes a single magical instrument, a instrument bag with a hidden weapon compartment, some of his finest musical works before he got insane, and his adventuring equipment (magical elven blade, an elven chain, and a magical cloak)
New Monsters:
Songhaunt: Songhaunt are incoperal undead capable of dealing charisma damage, and sonic based effects with they moans.
Spectral Bard: see the description of Laleth for possible powers and defenses.