Halaster Blackcloak

Halaster wears a robe of eyes that lets him see in all directions, gives him darkvision out to a range of 120 feet, grants advantage on Wisdom (Perception) checks that rely on sight, and allows him to see invisible creatures and objects, as well as into the Ethereal Plane, out to a range of 120 feet.

Halaster wields a blast scepter (a very rare magic item that requires attunement). It can be used as an arcane focus. Whoever is attuned to the blast scepter gains resistance to fire and lightning damage and can, as an action, use it to cast thunderwave as a 4th-level spell (save DC 16) without expending a spell slot.

Halaster also wears a horned ring (a very rare magic item that requires attunement), which allows an attuned wearer to ignore Undermountain's magical restrictions (see "Alterations to Magic").

When he finishes a short rest, Halaster recovers all his spell slots of 5th level and lower.

1/DAY

If Halaster fails a saving throw, he can choose to succeed instead.

3/DAY

If Halaster dies in Undermountain, he revives after 1d10 days, with all his hit points and any missing body parts restored. His new body appears in a random safe location in Undermountain.

Halaster is a 20th-level spellcaster. His spellcasting ability is Intelligence (spell save DC 22, +14 to hit with spell attacks). He can cast disguise self and invisibility at will. He can cast fly and lightning bolt once each without expending a spell slot, but can't do so again until he finishes a short or long rest. Halaster has the following wizard spells prepared:

• At will: disguise self, invisibility.
• 1/day: fly, lightning bolt.

• Cantrips (at will): dancing lights, fire bolt, light, mage hand, prestidigitation
• 1st level (4 slots): mage armor, magic missile, shield, silent image
• 2nd level (3 slots): arcane lock, cloud of daggers, darkvision, knock
• 3rd level (3 slots): counterspell, dispel magic, fireball
• 4th level (3 slots): confusion, hallucinatory terrain, polymorph
• 5th level (3 slots): Bigby's hand, geas, wall of force
• 6th level (2 slots): chain lightning, globe of invulnerability, programmed illusion
• 7th level (2 slots): finger of death, symbol, teleport
• 8th level (1 slots): maze, mind blank
• 9th level (1 slots): meteor swarm, wish

Halaster uses his blast scepter to cast thunderwave as a 4th-level spell. Each creature in a 15-foot cube originating from him must make a DC 16 Constitution saving throw. On a failed save, a creature takes 5d8 thunder damage and is pushed 10 feet away. On a successful save, the creature takes half as much damage and isn't pushed

Halaster can take 2 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Halaster regains spent legendary actions at the start of its turn.

2/TURN

Halaster casts a spell of 3rd level or lower.

Halaster expends a spell slot of 4th level or lower and gains 5 temporary hit points per level of the slot.

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.

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.