RoleAids Demons in Planescape

Sciborg,
This is essentially a lark. I figure, why let good statistics and ideas go to waste? I figure there's no such thing as an unusable idea, so we may as well try and make 'em work for Planescape. For my part, these aren't thoroughly considered ideas, it's more an attempt to start a dialogue on using these creatures, where they might fit in, if any of the fluff from the Demons set (and there was quite a bit for essentially a monster compendium) could be reused or repurposed, etc.

Lord Dorndigaffe - Arch-Duke of Torments
{for this build, the alignment will need to be changed to Lawful Evil} Lord Dorndigaffe, devilish duke of the torments, is considered to be the vile "saint" of Abishai. Where the lowly, multi-colored Baatezu have been "leased" to Tiamat to guard her realm, Dorndigaffe frequently borrows them to teach them about torturing the loathsome souls that have been consigned to the Nine Hells. Dorndigaffe appears similar to a Red Abishai, though he is taller, frequently dons a cloak , and is always surrounded by the scent of rot and corruption. While largely considered to be amongst the rabble of devil-kin that inhabit Avernus, Dorndigaffe has also been known to taste of the sweet torments available in Phlegethos, though he is always in disguise so as not to be caught sponging secrets from the Lady Fierana and Lord Belial.

Lord Thruxus - Master Tempter
{for this build, let's assume Thruxus is Neutral Evil. Also, if you like Hellboy comics, think Koku, the majordomo of Baba Yaga} Thruxus typically takes the most innocuous form possible: that of a small, mischievous child. That shouldn't fool anyone, though, for Thruxus is a powerful Altraloth allied with the Oinoloth. Thruxus represents the seductive side of the Yugoloths, dispensing gifts as his master (and for that matter, himself) deems necessary. All his gifts are given complete with warnings, typically in the form of impenetrable riddles, but nonetheless, the corrupting aspect of his gifts is always related to his victims. Thruxus' typical scheme is one of "high short-term benefit, but destructive long-term ramifications." Thruxus can always be found near the Siege Perilous, ready to dispense the vile gifts of Khin-Oin.

Grand Polyphon: Prince of the Mind, Lord of Deception
This mass of ooze and ninety-nine fanged, forked-tongued mouths lairs in several holes throughout the Plane of Infinite Portals, slithering his way through tunnels and sewers into many of the palaces ruled by Tanar'ri lords. As a former grand general of the Obyirths, and a former duke that was cast down by Fraz Urb'lu'u, Lord of Deception, Polyphon foments the rebellions amongst the petty beasts that hope to gain control of the uppermost layer of the Abyss. Ancient texts claim that Polyphon's role amongst the Obyirths was as a representation of the creeping hatred that results from trying to determine what is truth and what is a lie.

Forneus, Duke of the Mind and the Heart, the Treacherous:
The Yugoloth lord Forneus outwardly appears to be one of the Jackal-headed Arcanoloths. However, while taken from amongst their ranks, this being was altered by the Night Hags to have his mouth sewn shut, a lying mouth gashed into the area where his heart should be, and a pair of eyes bored into the back of his skull. Lairing deep in forgotten corners of Khin-Oin, Forneus practiced the art of lying, stealing, murdering and developed martial skills of a talented warrior and assassin, in addition to knowing a measure of dark arts. Forneus has since been directed by the General of Gehenna to keep the most powerful of Gehenna's volatile inhabitants from ever coming to an agreement. Graz'zt is also said to have targeted Forneus for his role in keeping the grand alliance from materializing. {change alignment to Neutral Evil}

Volak, Duke of the Mind and the Soul: the False Prophet
Volak bears a prize role within Asmodeus's ranks. As the duke of false prophecies, he preaches tales that ultimately lead his faithful to acts that trend away from faith in the gods of good. Over a long enough period of time, their actions lead to the embrace of powerful evil mortals that commit atrocities in the name of stability. All Baator smiles when Volak speaks his black lies of the future.

Andrealphus, Duke of the Mind and the Flesh, the Demonic Highwayman
Andrealphus is one of the few Abyssal Princes that spends significant time amongst the Great Road in the Outlands. This Tanar'ri lord steals from all he meets, and maintains a small cadre of thugs in the town of Plague-Mort to do his bidding. After Andrealphus robs his victims blind, he often sends out the thugs to capture his victims and drag them back to the Abyss to have their souls added to the larvae that crawl through the Plane of Infinite Portals. In order to keep from having to recorporate himself in the muck of the Abyss, he keeps a phylactery atop an enormous tower in the center of a lake that is incredibly far from any roads. He is utterly untrustful, even towards those he typically associates.

Eligos, Duke of the Mind and the Blood, Lord of Madness:
Eligos has a strange position within the Abyss, as he is one amongst many Abyssal Lords that focus on madness. Appearing like a gaping maw with thousands of lashing tongues, it is believed by some antideluvian scholars that Eligos lairs invisibly in the realm inhabited by Diinkarazan, his gibbering words driving the Duergar God mad.

Grand Decarabia, Duke of the Flesh, Lord of Lust
{change alignment to neutral evil} Various theories amongst the Arcanaloth philosophers (though, needless to say, little talked about amongst other beings) attempt to explain the blank slate that is Decarabia: it is, after all, exceedingly strange that, of all the infernal species, the Yugoloths have no caste specialized in seduction, and yet they do have an Altraloth tasked with just that task. Two theories hold the most sway: either he was a baern in the earliest eras from whom the first erinyes and succubi/incubi were formed, or he is a grand experiment in providing ultroloths a purpose beyond their innate innefability. Decarabia's faceless nature essentially reflects back at any individual what they wish to see, and his hands always hold items of the utmost capability to sway those he meets to his side. Where the continuous war in Oinos is said to wear away the capability for the individual to understand or comprehend atrocity, the hedonistic lair Decarabia keeps in that layer of the Gray Wastes is said to strip away the capability of an individual to understand sensuality and tactility.

Vapula, Duke of Greed
Vapula is frequently whispered of, but little experienced, throughout any urban area of the Abyss, and even unto Plague Mort. It is well known that Vapula takes the form of a small beggar child, of which the Abyss is possessed of vast quantities. However, Vapula uses that form to seem inconsequential and learn secrets. He then uses those secrets to convince those around him to amass wealth: a whisper of a valuable treasure, a secret of uncounted wealth available if one acts the interest of the whole. Vapula loves bankers, as they always spill secrets for him, even as they pass him by as unworthy of their attention: their secretes are then used to seduce other bankers to screw over the populace to line their own pockets.

Gremory, duke of the flesh and the mind, the Envious
Gremory is easily the least subtle Abyssal Prince attempting to steal a layer from the Abyssal Lords. He is in no position, in terms of power, to accomplish that task. In the meantime, he covets the allegiance of Arch-Lictor Rannison of Plague-Mort. Well known, in the Abyss at any rate, for his capability to inspire a loathing of all religions (mostly through his tendency to change religious allegiance on an irregular basis), Rannison actually follows no whim but his own. Gremory has sent gifts and threats, alike to try and draw Rannison from his allegiance to himself. Ironically, what Gremory wants is a mind as wicked and keen as Rannison's.

Rofocale, Lord of the flesh and soul, the gluttonous
Rofocale, the corpulant lord, is a vassal of Dis Pater, doing his will in Avernus. Rofocale does little more than eat a lot in order to seal mercantile deals with the rabble of Devilkin.

Last of the Dukes!

Phenex, Prince of the Blood, the Raging Lord
Phenex is a vassal and frequent rival of Marduk, blazing lord of the Balor demons in the Abyss. When under Marduk's control, Phenex is frequently turned loose to drive his enemies into a rage and have them turn against each other. When under the minimal control he can muster, Phenex is also a competent general that always, ALWAYS, battles using scorched earth tactics.

Gusion, Duke of the Blood and the Heart
{change alignment to NE} Gusion is an altraloth lord inhabiting the plane of Carceri, leading a cadre of assassins in support of whichever side of the Blood War holds his contract. Gusion holds a special loathing for the Titan's pride, and frequently murders their servants and placing evidence that implicates the Greek Gods. It is believed that Gusion is particularly loathed by Hades, but the arcanaloths smile enigmatically when asked.

Botis, duke of the blood and the soul
Botis wanders a lonely forest in Avernus, wherein suicide victims' souls are shaped into lanterns or their ectoplasm is used to water the trees. Botis is particularly hated by most good gods, as he frequently steals their followers for his forest. As the lord of suicides, his role in the Blood War is to convince mortal realms on the cusp of invasion that there is no defense against the Devils, and that they are better off dead before they are overrun. He has a close relationship with Bel, owing to the role he played in the destruction of Carthage.

Furfur, Duke of the blood and the mind
Furfur is actually an infernal being that owes no allegiance to the Demons, Devils, or Daemons, having sprung from the very soil of Carceri. Furfur repeatedly manages to escape the plane, but is always dragged back kicking and screaming. He is capable of moving his palatial estate around Carceri, and inevitably attempts to steal some being's land in the process. For being in Carceri, he always places it in the most ideal real estate. His theft always is noticed by whatever Ghereleth, Defier, Night Hag, Titan, or other infernal being he attempts to steal from, and they inevitably throw him out. His stupid pride continuously puts him back in the same position, though.

Sabnock, Duke of teh Blood and the Flesh
As the devilish lord of depravity, Sabnock gladly pursues the goals of Belial and Fierana. His pierced body is frequently used to demonstrate horrors that will be visited upon the souls in their realm. Some believe his craven nature is a ruse, but there are other whispers that say that Sabnock once held a higher position of power in the Nine Hells, but was cast down so thoroughly that it broke his spirit. These same whispers say he was then plucked from Avernus by Belial to demonstrate that no spirit, no matter how powerful, cannot be broken.