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.


 * Dormitories:


 * Halaster's sanctuary:


 * Headmaster's sanctum:


 * Lecture hall:


 * Spellcasting hall:
 * This room had a 30' (9.1 m) high vaulted ceiling and was illuminated by continual flames that filled the claw-shaped sconces that lined its walls. These walls, along with the 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 sanctum:

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.

Inhabitants

 * 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.