1-10

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).

11-20

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.

21-30

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.

31-32

The contents of one character's backpack are mysteriously shuffled around.

33-34

A nonmagical item in one character's possession changes appearance slightly. This transformation is permanent.

35-36

A gate opens in the ceiling and something falls out of it, after which the gate closes and disappears (generate a random trinket).

37-38

Heavy mechanisms grind loudly behind a wall or under the floor for 1 minute.

39-40

A floating light seen in the distance disappears if anyone gets too close to it.

41-42

All the characters have their hair suddenly stand on end for 1 minute.

43-44

Time freezes briefly for all but one character.

45-46

Thin cracks form along one wall.

47-48

A brief, mild earth tremor stirs up dust but causes no damage.

49-50

Candles, torches, and campfires burn with green flame for the next Roll 1d4+1 hours.

51-52

An unseen servant delivers a plate of Resolve: {hot buns|a bowl of fresh fruit} to the party.

53-54

Roll 1d4+1 live chickens materialize nearby.

55-56

A 1-foot-high waterspout jets up from the floor and lasts for 1 minute. The water is cold and fresh.

57-58

Any empty wineskins, waterskins, or canteens carried by the characters are magically replenished.

59-60

A light breeze blows through the area, carrying the scent of lavender and lilac. When the breeze fades, the characters' clothing and great have all been magically cleaned.

61-62

A button appears on a wall that rings a hidden bell when pushed.

63-64

A chalk "X" appears that marks a secret compartment that contains the following note written in Common: "Ha! Beat you to the treasure! Sincerely, X the Mystic."

65-66

A magical pebble bounces around the room.

67-68

An invisible corpse sprawls across the floor.

69-70

An illusion of Halaster appears and says "The right way is left!" or something similarly cryptic and useless.

71-72

A coin slot in the wall labelled "Undermountain Repair Fund" materializes.

73-75

A silent, spectral hand beckons the characters to follow it.

76-77

A character is given a vision or insight of the bones of an adventurer buried beneath their feet.

78-79

A harmless patch of mold on a wall changes shape to mimic the face of Resolve: {the nearest party member|Halaster}.

80-81

All knots and buckles on the characters' persons are magically undone.

82-84

A magic mouth speaks words of warning or points the characters in a specific direction.

85-86

A beholder-shaped pinata dangles from the ceiling. If broken open, it contains Resolve: {candies|10000 cp|a swarm of spiders}.

87-88

A stuffed doll resembling one of the characters has a dagger stuck through its chest.

89-90

An Undermountain secret is scrawled on the wall (draw a card for it).

91-95

Undermountain crackles with wild magic for the next Roll 3d20 minutes; during that time, all spells cast of 1st level and higher come with a D10000 Wild Magic Surge.

96-100

Magic shorts out in Undermountain and it becomes a dead-magic zone for the next Roll 3d20 minutes, as though it were in an antimagic field. Halaster and anyone else attuned to a Horned Ring is unaffected.

101-110

A randomly-determined adventurer is telepathically contacted by the voice of Jhesiyra Kestellharp, who Resolve: {gives them a cryptic warning of a nearby threat|cryptically muses on the history of a nearby dungeon feature or denizen}.

111-112

For the next Roll 1d60 minutes, the first time a creature on the level targets another creature with a spell, the caster must make a DC 11 saving throw using its spellcasting ability. On a failed save, the spell targets the caster instead. On a successful save, the spell functions normally. This effect then ends.

113-114

A warping, shimmering cloud of obscuring fog appears, expanding 10 feet per 6 second round for Roll 2d6-1 minutes, then disappearing. A creature immersed in the fog teleports as it loses sight of its surroundings, emerging from the fog in Resolve: {a random room on the current level|a random room on the next level|a random room on level Roll on "RandomLevelUpweighted"}.

115-116

All fire on the level freezes into ice that gives off a blue light equal to the illumination it normally provides. In addition, the level radiates extreme cold for Roll 1d20 hours. A creature exposed to the cold must succeed on a DC 10 Constitution saving throw at the end of each hour or gain one level of exhaustion. Creatures with resistance or immunity to cold damage automatically succeed on the saving throw, as do creatures wearing cold weather gear (thick coats, gloves, and the like) and creatures naturally adapted to cold climates.

117-118

A strong wind blows through the level for Roll 1d60 minutes. A strong wind imposes disadvantage on ranged weapon attack rolls and Wisdom (Perception) checks that rely on hearing. A strong wind also extinguishes open flames, disperses fog, and makes flying by nonmagical means nearly impossible. A flying creature in a strong wind must land at the end of its turn or fall.

119-120

Gravity re-orients to pull Resolve: {north|south|east|west|upwards|upwards} for creatures on the current level for Roll 3d20 minutes before returning to normal. The pull is gentle at first - for the first Roll 1d6 rounds of the effect, a falling creature's rate of descent slows to 60 feet per round and it takes no falling damage. After that duration, gravity is fully effective.