Dweomercore

Dweomercore was an arcane academy that comprised the 9 level of the subterranean dungeon-complex known as Undermountain. Founded by the "Mad Mage" Halaster Blackcloak himself, it attracted malevolent mages who sought magical knowledge and opportunities to educate their pupils in the Art.

As of the Year of the Three Ships Sailing, 1492 DR, Dweomercore was overseen by an anonymous arcanaloth who served as the academy's headmaster, who in turn was aided by the night hag Wormriddle.

Description
Built from the remnants of a former underground mansion, Dweomercore had all the trappings that would be expected of any academy dedicated to the practice of arcane magic. It was well furnished, and featured a number grand lecture halls, workshops dedicated to the art of potion-brewing and spellcasting, an expansive library and dedicated classrooms for focused study on each of the schools of magic.

Entrances
Only one entrance to Dweomercore was commonly known:
 * A passageway from Slitherswamp led directly to the entry hall of Dweomercore.

Notable Locations

 * Classrooms:
 * Dweomercore featured a number of classrooms, within which students could study the Art in more intimate environment than was available in the lecture hall. Select classrooms were dedicated to the various schools of magic and were imbued with their respective magic:


 * Conjuration: The domed conjuration classroom featured a a large pentagram that was inscribed upon its floor. Any fiend that was summoned within the symbol were permanently trapped within its confines on the Prime Material plane until it was released, damaged or another being was conjured. The summoning symbol itself could be damaged, after which any trapped creature would then be released.
 * Illusion: This classroom appeared as the courtyard of a grand, ivy-covered Waterdhavian villa that was always illuminated by the warm mid-afternoon sun. A large fountain featured a centerpiece sculpture of a trident-wielding sahuagin that was encircled by white marble benches. An illusory tiefling in flowing golden robes, who referred to himself as Professor Figment, expounded upon the nature of illusion magic, its applications and famous practitioners. Attempts to dispel the "professor" or the scenery of the classroom resulted in the appearance of a phantasmal killer or the effects of the spell weird.
 * Necromancy: The walls and roof of this domed classroom were decorated with hundreds of humanoid skeletons. Set upon the floor was a pair of concentric circles, with an annulus of necromantic glyphs that radiated a faint purple glow. Any undead creature raised within the symbol became exceptionally resilient, specifically against being turned by clerics. The necromancy classroom was frequented by the archmage Nester, who appeared as a floating skull and pair of skeletal arms after a partially-failed attempt at achieving lichdom.
 * Transmutation: Illuminated by several continual flames placed into sconces on its walls, this classroom changed hue as the colors of the flames changed every minute. The floor of the room was inscribed with a 20' (6.1 m) diameter circle inset by an equilateral triangle, the symbol of thaumaturgy, that radiated a faint magical aura. Any creature or object under the effects of a transmutation spell retained the effects in a permanent manner until they were removed from the border of the symbol. A 10' (3 m) wide iron cage was placed just to the side of the arcane symbol.


 * Detention area:
 * This hallway featured a long hallway with six alcoves that each held an iron-barred cell that was magically locked. The creatures within could be freely used by students as subjects for their experimentation. Just south of the cells was a "statue" of a dragonborn wizard who had been petrified by means of a wish spell by Halaster some time before the 14 century DR. Beneath the statue was an inscription: "Follow the rules. Obey your instructors. Don't be this guy."


 * Dining hall:
 * The dining hall of Dweomercore featured a grand, stone dining table with a dozen wooden chairs that allowed the academy's students to enjoy their meals with one another. It was well-let by a pair of continual flame lanterns and decorated with a large tapestry that hung on its north wall. This tapestry depicted Halaster's original apprentices, collectively known as the Seven: Arcturia, Jhesiyra Kestellharp, Muiral, Nester, Marambra Nyghtsteel, Rantantar and Trobriand.


 * Six living unseen servants served the pupils their meals and cleaned up after they were finished. Meals were prepared by a pair of barbed devils from within the kitchen and larder, located down the hall just northeast of the dining room.


 * Dormitories:
 * Located in the northwest section of the academy were the ten bed chambers that were made available to its students. They were identically furnished with a plain bed, iron-banded footlocker and a desk complete with quills, jars of ink, scroll paper and similar scholarly implements.


 * Halaster's sanctuary:
 * Halaster maintained a private chamber in Dweomercore, located behind a rather plain-looking single door. Just beyond the door were two 11' (3.4 m) tall statues of humanoid figures that each possessed the head of an elephant. One of these statues was in fact a stone golem while the other was completely inanimate. At the end of this small chamber was a raised dais that stood before a set of double doors, in each of which was carve the face of a screaming devil. Atop the dais floated the spectral skull composed form of pure magical force, that appeared in the form of a bearded human man.


 * Beyond the doors was Halaster's personal study, which included his work desk and his black crystal chair. It was possible to find one of Halaster's spellbooks within the drawers of this desk.


 * Headmaster's sanctum:
 * Down the hallway east of the academy's main entrance was the office and lair of Dweomercore's arcanaloth headmaster. Within his office was a life-size statue of Halaster and a magnificent oak desk behind which sat a high-backed chair. Just beyond this room, behind a secret door, was his personal chamber that was protected by a necrotic symbol inscribed upon the floor beneath a circular area rug. The walls of the circular room were inset with stone bookshelves that contained dozens of rare tomes that had been gathered from across the Realms and beyond. Within the collection were many books that covered mundane topics such as art, etiquette and oration; a score of treatises that detailed the Outer Planes; along with grand history books that spanned the histories of Toril along with other planets such as Oerth and Athas.


 * Lecture hall:
 * In the northeast corner of Dweomercore was a vast lecture from, within which students observed demonstrations and lectures given by their professors. A large chalkboard was mounted on the southern wall, beneath which was a 5' (1.5 m) high stone dais. The upward-sloping floor held several rows of stone benches that provided the students ample space to clearly see the orator. The hall was illuminated by several continual flames that burned within stone scones set into the walls.


 * Spellcasting hall:
 * This room had a 30' (9.1 m) high vaulted ceiling and was also illuminated by continual flames set within claw-shaped sconces. Its walls, along with its ceiling and floor, were scorched and otherwise marred by errant spells that were cast by the academy's pupils. Within the hall were three indestructible, life-size statues of robed human spellcasters that radiated an aura of transmutation magic. They were in fact constructs that sprang to "life" when a person or creature passed through the room's center.


 * The east statue depicted a Shou woman clutching an orb whose face had been disfigured by some sort of acid.
 * The west statue was a long-haired woman wearing a mask and carrying a distinct, gnarled wand.
 * The south statue, which stood atop a stone dais, was carved in the form of Halaster Blackcloak adorned in a robe of eyes and carrying a magical staff.


 * Wormriddle's santcum:
 * The night hag Wormriddle kept her den and private chambers in a series of rooms east of the lecture hall. Her den was decorated with several mummified cats and a collection of crudely-fashioned dolls in the likeness of Dweomercore's students. These dolls imbued with malevolent magical enchantments that allowed the hag to harm the students in a manner dependent on how she manipulated the doll: a needle to the doll's eye would blind them while piercing it with a knife left the student paralyzed.


 * Next to her lair was an arcane worship, filled with deceased bodies and dismembered limbs and other body parts. It was from within this putrid-smelling room that Wormriddle created the flesh golems she kept under her command.

Exits
The following ways could be used to leave Dweomercore:
 * A pit in the middle of the academy dropped straight down to Muiral's Gauntlet.
 * An archgate located near the conjuration classroom opened up a portal to the domain known as Arcturiadoom.
 * South of Halaster's chamber was a secret door that opened up into a corridor that descended to Muiral's Gauntlet.

Staff

 * Arcanaloth: An ally of the Mad Mage, it employed nycaloths and mezzoloths, and granted safe passage in exchange for magic items or assassination of the rampaging bone devil.
 * Wormriddle: Proud commander of four flesh golems, she was ready to offer spells in exchange for souls and wore a mummified kitten's head, because of her fear of felines, from cats to Tabaxi.

Students

 * Spite Harrowdale, a Rashemi human archmage in the guise of a twelve-year old boy, with an oni companion.
 * Cephalossk, a lonely mind flayer arcanist with a hatred for Spite Harrowdale.
 * Nylas Jowd, a Thayan mage already enrolled in the Red Wizards of Thay, with two invisible will-o'-wisp companions.
 * The Horned Sisters, Turbulence and Violence, were tiefling mage sisters who tried to join the Arcane Brotherhood in Luskan and were denied. After staying in Skullport for a few years, they ended up here.
 * Elan Tanor'thal, a drow mage whose house ran a slave-trading business in Skullport but was driven out by the Xanathar's Thieves' Guild.