This appendix contains information on Halaster Blackcloak, as well as monsters and NPCs not found in the Monster Manual. After the Mad Mage, the creatures are in alphabetical order.
Halaster Blackcloak
Halaster Blackcloak, the Mad Mage of Undermountain, is the deranged individual behind most of the traps and horrors found in the great dungeon under Waterdeep. Undermountain is his home, an amusement gallery in which others perform to entertain him.
The Mad Mage knows the ever-changing ways of Undermountain as no one else does, for he is the one who controls those changes. He prefers to remain unseen, skulking about invisibly or peering through scrying sensors that resemble wide-open eyes surrounded by sparkling motes of light.
Halaster’s abilities far exceed those of most mortal wizards. His expertise with magic gates allows him to travel far and wide to engage in magical research. He spends much of his time creating gates, moving them around, and casting elder runes on them. Halaster’s gates connect the different levels of Undermountain, thus enabling him to bring new monsters into the dungeon to replenish those that die or escape. Even as groups of adventurers try to gain decisive control of just a small section of Undermountain’s halls, Halaster constantly alters the dungeon’s perils to thwart them.
Halaster’s true form is that of a tall, gaunt, male human, but he uses magic to take on many other visages and shapes. No matter what form he wears, the Mad Mage giggles and mutters incessantly. Contrary to appearances, however, Halaster is alert and attentive to the activities and preparations of all beings near him. He never willingly enters combat without first casting
Halaster’s Lair
As the master of Undermountain, Halaster can alter the entire dungeon to some extent. His lair actions and regional effects don’t extend beyond Undermountain.
Lair Actions
On initiative count 20 (losing initiative ties), Halaster takes a lair action to cause one of the following effects:
- Halaster targets a volume of unoccupied space or solid stone no larger than four 10-foot cubes within 30 feet of him, turning the open space to solid, worked stone or vice versa.
- Halaster causes one door or archway within 30 feet of him to disappear and be replaced by a blank wall, or he restores a door or an archway previously removed in this way.
- Halaster deactivates or reactivates one of Undermountain’s magic gates. The gate must be within 120 feet of him.
Regional Effects
When Halaster is in Undermountain, the following effects can occur in any location within the dungeon or in any extraplanar extension of the dungeon:
- A magical scrying sensor appears, taking the form of a ghostly, 1-foot-diameter humanoid eye surrounded by motes of light. The sensor is stationary, though Halaster can reorient the eye to face in any direction. Halaster can see through the eye as though he was in its space. The eye can’t be harmed or dispelled, but it winks out within an antimagic field. A scrying eye lasts until Halaster ends the effect (no action required).
- A minor illusory effect is triggered, as though Halaster had cast
minor illusion in an area. Common illusions include the echo of rattling chains, the distant sound of explosive spells being cast, a dusty cloak or a rusty helm floating as though worn by an invisible figure, and illusory footprints appearing on a dusty floor. - Silent apparitions of dead adventurers drift through halls and rooms as though they are lost. An apparition can’t be harmed, and it doesn’t acknowledge creatures or objects in any way. It can’t be dispelled but is suppressed within an antimagic field.
Archdruid
Archdruid watch over the natural wonders of their domains. They seldom interact with civilized folk unless there is a great threat to the natural order, and their lairs are often guarded by allied beasts, plants, and fey.
Champion
Champion are mighty warriors who honed their fighting skills in gladiatorial pits. To soldiers and other people who fight for a living, champions are as influential as nobles, and their presence is courted as a sign of status among rulers.
Githyanki Gish
Their keen minds and psionic gifts allow the githyanki to master magic. Githyanki Gish blend their magical abilities with swordplay to become dangerous foes in battle. Their specialized capabilities make them well suited for assassination, raiding, and espionage.
Lava Child
Physically identical to one another, Lava Child have muscular builds and childish, perpetually grinning faces. Most are born in the Fountains of Creation, also known as the Plane of Magma, which is wedged between the Elemental Planes of Earth and Fire. Within volcanic caverns, lava children form communities, serving primordial beings out of fear or worshiping gods of earth and fire.
Though they’re not violent by nature, lava children fiercely defend territory they claim as their own. Many intruders have been fooled by a lava child’s smile, believing themselves welcome when in fact they’re about to be torn limb from limb. Lava children typically stick close to their lairs, but actively hunt when food grows scarce.
Lava Born
The first lava children were created by the merging of spirits of earth and fire. Upon reaching adulthood, a lava child gains the ability to procreate by itself. An adult lava child lays several eggs in its lifetime, which is roughly fifty years. These eggs incubate in pools of molten magma until they hatch. The pink, smiling newborn matures at the same rate as a human. The parent protects its offspring until the new lava child is strong enough to defend itself and forage on its own. Lava children eat meat, bones, paper, plants, and just about anything else not made of metal or stone. Cooked meat is their favorite.
Living Spell
Areas of wild magic and sites that have been ravaged by powerful eldritch forces can give rise to spell effects that refuse to dissipate. These so-called living spells haunt the places where they were created, subsisting on ambient magical energy.
A living spell appears much like a normal spell effect, except that its magical energy lingers and moves with purpose.
Constructed Nature
A living spell doesn’t require air, food, drink, or sleep.
Magical Essence
The process that creates a living spell changes the nature of its magic. A living spell isn’t subject to
Living Unseen Servant
Like an overzealous butler or maid, a living unseen servant spell busies itself with tasks in hopes of pleasing its creator. It can wield simple weapons but prefers not to.
Muiral
Muiral was an accomplished human warrior who long served as Halaster’s bodyguard. His descent into madness began when he asked the Mad Mage to tutor him in the wizardly arts. Muiral learned enough magic to transform himself into a half-scorpion monstrosity, becoming known as Muiral the Misshapen. He then retired to the level of Undermountain that would later be called Muiral’s Gauntlet, driving out and slaying its original drow denizens. Muiral now spends his days hunting adventurers and other interlopers for fun. Long years alone—and Halaster’s influence—have rendered him utterly insane.
Neothelid
When an illithid colony’s tadpoles are no longer fed by their caretakers, they turn to devouring one another out of hunger. Only one tadpole survives out of the thousands in the colony’s pool, and it emerges as a neothelid—a slime-covered worm of immense size.
A feral thing, a neothelid knows nothing beyond the predatory existence it has lived so far. It prowls subterranean passages in search of more brains to sate its constant hunger, growing ever more vicious.
Scaladar
Scaladar are constructs created by Trobriand, one of Halaster’s apprentices. They move and attack like giant scorpions, grabbing prey with two large pincer claws and delivering a deadly pulse of lightning with their metal stinger tails.
Trobriand’s Rings
Trobriand crafted magic rings to control the scaladar. Each ring is a black metal loop with a stinger-shaped protrusion. No scaladar can harm the wearer of such a ring, and any scaladar within 100 feet of a ring wearer must obey its spoken commands. The magic of the ring enables the scaladar to understand and interpret these commands, even though the creatures have no language of their own. If given contradictory commands from two different ring wearers, a scaladar immediately shuts down and becomes
Constructed Nature
A scaladar doesn’t require air, food, drink, or sleep.
Shadow Assassin
A shadow assassin looks like an undead shadow (as described in the Monster Manual) that wields shortswords also made of shadow. It exists only to slay the living.
Undead Nature
A shadow assassin doesn’t require air, food, drink, or sleep.
Ulitharid
Very rarely, an illithid tadpole transforms an individual into an ulitharid rather than an ordinary mind flayer. Ulitharids are larger than mind flayers and have six tentacles instead of four. Illithids innately recognize that an ulitharid’s survival is more important than their own. In most colonies, an ulitharid becomes an elder brain’s most favored servant, invested with power and authority. In others, the elder brain perceives the ulitharid as a potential rival, manipulating or quashing the ulitharid’s ambitions accordingly.
When an ulitharid finds sharing leadership with an elder brain to be insufferable, it breaks off from the colony, taking a group of mind flayers with it, and forms a new colony. After the death of the ulitharid’s body, mind flayers place its brain in a brine pool, where it grows into an elder brain over a few days.
Extractor Staff
Each ulitharid carries a psionically enhanced staff made of black metal. When the ulitharid is ready to give up its body, it attaches the staff to the back of its head and uses the staff to crack open its own skull and peel it apart, enabling its brain to be extracted and placed in a brine pool, where it can grow into an elder brain. The staff serves no other purpose.
Werebat
A werebat is a humanoid afflicted with a rare form of lycanthropy that enables it to transform into a giant bat or a bat-humanoid hybrid. (See the Monster Manual for more information on lycanthropy.) Most werebats are of goblin stock.
Deep Dwellers
Werebats are shunned even by goblin society because of their need to feed on blood to survive. They prefer to lair in dark places, such as attics and caves, and typically adopt nocturnal hunting habits.
Blood Drinkers
A werebat must consume at least 1 pint of fresh blood each night, or it weakens and gains one level of
Werebat Lycanthropy
A player character who becomes a werebat gains a Dexterity of 17 if their score isn’t already higher. Attack and damage rolls for the werebat’s bite attack are based on the character’s Strength or Dexterity score, whichever is higher.
