While enrobed in a black velvet cape and suit of midnight blue finery, this mask-wearing villain is no man, nor beast, nor even undead. Even the clothes it wears down to the exquisite larva-style mask of porcelain are nothing more than an illusion. It’s difficult to understand how the complex harmonies of this elemental actually produces this dashing image, many composers have gone mad attempting to replicate it. It doesn’t help that Phantasmagoria encourages such exploration. With a fluctuation of sound, this foe can materialize a faux-saber out of nothing, but it still cuts just as deep. In its true form, Phantasmagoria retains most of its humanoid traits, though they are jumbled and distended in a discordant mess.

Phantasmagoria came to be due to an absurd tragedy. During a sold-out performance of a grand opera, including a full chorus and orchestra, the opera house was struck by an arcane explosion set off by revolutionaries looking to kill the upper class inside. They succeed, obliterating all within along with the five metropolitan blocks around it in the space of a breath. It happened at the same moment of the show’s rousing crescendo with most of the audience singing along. The rush of anguished and ecstatic sounds gave birth to an element of sound itself. One with an agenda, to compose and perform pieces of equal measure. Body counts didn’t matter, no sacrifice was too great for art.

Decadent Soulless. Along the way, Phantasmagoria learned to appreciate the way that the rich and famous live. It soon adopted a masked persona so it might indulge, albeit tangentially, in the finer things in life. Along the way, the elemental amassed a fortune and a string of contacts among the kingdom’s elite. Soon, it became a mysterious patron to various musical artists, though those it graces with its attention usually live short, intense lives which end in fame-cementing tragedy. This tickles Phantasmagoria even more.

Phantasmagoria

Medium elemental, neutral evil

Armor Class 17 (natural armor)

Hit Points 119 (14d8 + 56)

Speed 50ft

Str 13 Dex 17 Con 19 Int 14 Wis 13 Cha 18

Saving Throws Wis +6, Cha +9

Skills Arcana +7, Deception +9, History +7, Performance +9, Persuasion +9

Damage Immunities thunder; bludgeoning, piercing, and slashing from nonmagical attacks that aren't silvered

Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, stunned

Senses darkvision 60 ft., tremorsense 60 ft., passive Perception 11

Languages Common, Elvish, Sylvan

Challenge 15 (13,000 XP)

Bind Instrument.

If Phantasmagoria has an instrument on its person for 24 hours it may choose to become bound to that instrument. While holding its bound instrument, Phantasmagoria has advantage on Performance checks. It can also cast the Misty Step spell but only to move closer to the bound instrument. Phantasmagoria must hold its bound instrument to use any Legendary Abilities besides Attack.

Innate Spellcasting.

Phantasmagoria's innate spellcasting ability is Charisma (spell save DC 17, +7 to hit with spell attacks). Any creature that is Deafened has advantage on saving throws against Phantasmagoria's spells. It can innately cast the following spells, requiring no material components:

At will: Dissonant Whispers, Illusionary Script, Message, Minor illusion, Tongues, Thunderclap, Thunderwave

3/day each: Calm Emotions, Magic Mouth, Shatter, Hypnotic Pattern

1/day each: Hallucinatory Terrian, Mislead

Magic Resistance.

Phantasmagoria has advantage on saving throws against spells and other magical effects.

Rejuvenation.

When slain, Phantasmagoria reconstructs its body in 24 hours if its bound instrument is intact, regaining all its hit points and becoming active again. The new body appears within 5 feet of Phantasmagoria's bound instrument.

Vulnerable to Silence.

Whenever Phantasmagoria starts its turn in the area of effect of the Silence spell or a similar effect, it has disadvantage on all attack rolls and skill checks. It must succeed on a DC 14 Consitution saving throw or be unable to Move this turn.

Thunder Form.

The elemental can move through a space as narrow as 1 inch wide without squeezing. A creature that touches the elemental or hits it with a melee attack while within 5 feet of it takes 5 (1d10) Thunder damage. In addition, the elemental can enter a hostile creature's space and stop there. The first time it enters a creature's space on a turn, that creature takes 5 (1d10) thunder damage and must succeed on a DC 17 Constitution save or be Deafened until the end of its next turn.

Actions

Multiattack.

Phantasmagoria makes two attacks.

Sonic Slice.

Melee Spell Attack: +9 to hit, reach 5ft., one target. Hit: 13 (2d8+4) slashing damage plus 5 (1d10) Thunder damage.

Legendary Actions

Phantasmagoria can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. Phantasmagoria regains spent legendary actions at the start of its turn.

Attack (1 point). Phantasmagoria makes one attack.

High Note (1 point). Phantasmagoria chooses a creature it can see within 30ft and batters it with painful notes. The creature must succeed on a DC 17 Constitution save or be Incapacitated until the end of its next turn.

Cast Spell (2 points). Phantasmagoria casts an available spell.

Musical Interlude (2 points). All creatures within 60ft of Phantasmagoria with an intelligence of 6 or higher must succeed on a DC 17 Wisdom Save or be swept up in its music and begin dancing.

A dancing creature must use all its movement to dance without leaving its space and has disadvantage on Dexterity saving throws and attack rolls. While the target is affected by this spell, other creatures have advantage on attack rolls against it. Affected creatures also cannot take Opportunity Attacks.

An affected creature stops dancing at the end of its next turn. Deafened creatures have advantage against this saving throw.

If at least 1 creature within 5ft of Phantasmagoria is affected by Musical Interlude, the elemental may also Move.