1d6 Random Demonic Vaults In The Wasteland Adventure Encounter Table For Your Old School Campaigns

Sealed for a billion years or more these vaults hold the darkest and most vile of artifacts and horrors from the war between the dreams of divinities. Many of the seals & wards have cracked releasing their charges into the wastelands of accursed Atlantis. Tribes of mutants, nomads and warriors avoid these places as taboo with  good reason but wizards, sorcerers, freebooters, and fortune hunters often seek these places out for collectors of occult ephemera. For with great profits come greater risks, and the demonic vaults present terrible opportunities for those who would use the magick forces of Hell for their gain or so they think. Anyone coming within a 30 foot radius of these places must make a save vs device or feel a telepathic buzzing scan as the minor demonic powers skitter through their minds not unlike mutant desert locusts. Their songs have been known to drive men mad. Anyone exposed to a newly opened vault will take 1d4 points of chaotically induced entropic damage every round as the alien energies warp and mutate the fabric of reality around them. There will be 1d4 minor demonic magick items in the area inside these vaults and 10% chance of a unique Marilith or greater demonic princess being present. These beings will have 1d8 unique mutations in addition to the standard abilities of these beings.
1d6 Random Demonic Vaults
In The Wasteland Adventure  Encounter Table

1. K'arharsarthl A maiden warrior of the 60th darkness whose savagery is only matched by her intelligence. She trades in super science artifacts and the souls of scholars as well as high level alchemists. This treacherous and dangerous minor divinity loathes wasteland dwellers and angels. She uses here abilities to torture wizards each and every chance she gets for magical formula. K'arharsarthl is able to cast magick at the 6th level from the black school and uses it to snare the souls of her prey in intricate webs. 
2. Otudakehamep has the head of a cuttle fish and aspects of a Deep One, she was a bride of Dagon at one time but has mutated in the wastelands to become far more reptilian, she feeds off the essence of angels through bizarre pseudo sexual rites. She uses a mix of dark magick spells of seventh level and mutations gained through repeated wasteland spawning. She uses both energy weapons and magick to gain the souls of her main prey angelic host soldiers and any underworld prey she finds. This warrior sports 1d4 mutations in addition to her normal abilities. She also hunts genie as well. She has the ability to phase in and out of the Dreamland's underworld at will. 
3. P'llaothotha The Scorpion Horror a mix of demon, mutant, and arachnid this creature is able to generate bio mechanical weaponry from within his body at will. He attacks demigods above all other prey except for mutants of which he has a special taste. Originally this monster was a demonic horror in the charge of one of the beings beyond the Threshold but he was betrayed by its master. He now hunts for the artifacts of that beings in the hope of ripping apart that being's soul. He will seek out wizards above all others for the sheer act of devouring their souls to learn their secrets. 
4. Uachothol is a sentient cancer given humanoid form and demonic powers, this thing has aspects of a Gug, slime, and undead giant given partially armored form. It is violence and alien blood given form. It seeks out the minds, hearts, and genitalia of wastelanders to read its own fate in the gore. This thing hates adventurers and kills clerics or priests on sight. It may also use the genitalia of wizards to create miniature versions of itself through spontaneous generation. Its main weapon is a phallic combination of magical sword and energy weapon given form. It sports 1d8 mutational powers and some minor demonic abilities. 
5. Yach-rthogos The Wind of Reversals , this demonic force is now nothing more then pure demonic soul energy and has the abilities of a shadow demon coupled with the abilities of a 7th level black mage of the worst aspect. It hunts for the angel that ripped its body and soul apart. It hates humans and wizards above all others and will rip apart and eat the souls of these beings. Its hunger is never ending and glutinous. It trades in information, bedtime stories, and eyes which it uses to see the future. 
6. Ggugngothaq &  Falulakorandug  The fused Lovecraftian horrors of demonic aspect whose forms were torn inside out and back again. These fleshly ever changing horror shows are collectors and devourers of dark aspect who trade in secrets, life, and artifacts of super science. They use their insane aspects to corrupt wasteland tribes to their cause of apathy and insane destruction. These worshipers are consumed and 1d4 hours later in the evening these twin horrors will birth forth 1d20 soldier demons of semi divine aspect. This is considered a sacrament and fetish of their worshipers, they have been known to play games of chance with certain powerful wizards but these end with the prey being murdered and their souls annihilated.