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In my campaign, there is a demon trapped in an artifact and forced to grant wishes. Though generally I rule wishes by intent and not trickery, this demon is of the monkey's paw variety and actively tries to turn the wish against the wisher. Because of the havoc that the artifact is currently causing, the party is prepared to destroy the artifact but this will have the downside of releasing the demon. I have created the demon but would appreciate commentary since I am not use to creating a monster at this level plus I am also trying something a bit different in how it does combat. Since the idea of the monkey's paw style of thinking is turning what a person does against them (or their allies), I am trying to have him not attack physically (despite giving him a weapon as a backup) but to redirect their actions in various ways. Also, given the spells listed, he comes from a strong magical background and relies more on that. The party has four 11th level characters though they handle CRs above that pretty easily (between their long experience in building characters and my choices in running the game).
Almost forgot: The spell Shared Pain mentioned is a non-consensual variant of Warding Bond where the recipient takes half the damage of the caster and neither party gets AC or saving throw benefits. Magus is a campaign setting language for magic.
So…too much, too little, anything that you might do a bit differently?
———–EDIT———–
Monkey King
Medium fiend, chaotic evil
Hit Points 157 (15d10 + 75)
Speed 40 ft.
Saving Throws Wis+8, Cha+11
Skills Deception+11, Intimidation+11, Persuasion+11
Damage Resistances cold, fire, lightning; bludgeoning,
piercing, and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities poisoned
Senses truesight 120 ft., passive Perception 13
Languages Magus, telepathy 120 ft.
Challenge (0 XP)
Proficiency Bonus 4
Armor Class 20 (natural armor)
STR 15,,DEX 22, CON 15, INT 15, WIS 18, CHA 24
Innate Spellcasting
The Monkey King's spellcasting ability is Charisma (spell save
DC 16).
The Monkey King can innately cast the following
spells, requiring no material components: • At will: Vicious
Mockery, Detect Magic, Dispel Magic • 3/day: Dissonant
Whispers, Tasha's Hideous Laughter • 2/day: Suggestion,
Crown of Madness, Phantasmal Force, Mirror Image, Major
Image, Phantasmal Killer , Shared Pain • 1/day each:
Confusion, Hypnotic Pattern, Mislead
Magic Resistance
The Monkey King has advantage on saving throws against
spells and other magical effects.
Reactive
The Monkey King can take one reaction on every turn in a
combat.
Magic Weapons
The Monkey King's weapon attacks are magical.
Telepathy
Can speak mentally with those around him and read surface
thoughts.
Mindful Defense
Due to being able to read surface thoughts of his opponents,
the Monkey King adds his Wisdom bonus in addition to his
Dexterity bonus to his Armor Class.
Actions
Multiattack.
The Monkey King makes four attacks with any combination of
his maul or unarmed strikes. Alternatively, it makes two melee
attacks and casts one spell.
+2 Maul.
Melee Weapon Attack:+8, Reach 5 ft., one target
Hit: 11 (2d6 + 4) bludgeoning damage
Unarmed Strike.
Melee Weapon Attack:+8, Reach 5 ft., one target
Hit: 9 (2d6 + 2) bludgeoning damage
Reactions
Pervert
If a creature casts a wish spell within the Monkey King's
hearing, he can adjust it away from the caster's intent.
Goad
If a creature is about to attack, the Monkey King can goad
them. On a failed Wisdom save, the attacker is at
disadvantage. If the attacker misses, the original (without
disadvantage) attack roll is misdirected to a creature adjacent
to the Monkey King that is within range of the attacker.
Trip
If a creature moves through any space adjacent to the Monkey
King, he can attempt to trip them.
Redirect
If a creature attempts to cast a spell on spell directly on the
Monkey King (i.e. not an area of effect), he can make a
Charisma saving throw against the caster's DC to redirect the
spell's target to other creature besides the caster within the
spell's range.
Best Answer
Overall, I like it. You have abilities that call back to monkey paw effects, it's what they asked for but not what they would "want". Yeah, overall solid design with your stated theme.
Alone against four 11th level characters I think it will likely die in a toe-to-toe fight. That said, it may not (depending on rolls) be an easy fight. But that's in line with what you said and "trying to have him not attack physically" with be key in the encounter. In a not toe-to-toe match, it could wipe them.
This will come down to the encounter layout. So, things like minions, terrain, and party readiness. Your stat block is good, it expresses your intent but all that is just the foundation. The layout will decide how easy/hard this is for the PCs.
EDIT There are community concerns that the above is largely subjective/opinion. However, this question and the answer given here touch on an important facet of ttrpg's in general, encounter design. That subject is not a "hard science" at all, hence it is a bit subjective. So, I am asking for a little leeway from the community.
The intent of this answer is to take a question on stat blocks in relation to difficulty and cast it as part of a greater structure, the encounter as a whole. This (encounter design) is a "softer science" as it must take into account how the players feel about the encounter and how that encounter fits within the story being told.
A prime example of this Tucker's Kobolds! The point of the original 1987 article by Moore was using your monster's effectively as a means of avoiding an all too common "arms race" personified by the philosophy, "bigger monsters, bigger danger".
So, let me lean into that now and provide a summary of what I'm saying.
In Summary
Stat blocks, while important are only a part of the encounter. The placement of the encounter makes a difference. The existence of allies, such as minions, makes a difference. Party readiness for the encounter at that point in time, makes a difference. The encounter in relation to your overall story, makes a difference. The encounter in relation to player expectations, makes a difference.