Merfolk Primma Donna

Medium Humanoid (Merfolk), Unaligned

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AC 19
HP 104 (16d8)
Speed 15ft., Swim 40ft. 
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STR:10 (+0) 
DEX: 18 (+4) 
CON: 14 (+2) 
INT: 13  (+1) 
WIS: 14 (+2) 
CHA: 20 (+5)
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Saving Throws - Dexterity +8, Cha +9
Skills - Athletics +4, Acrobatics +8, Insight +6,  Performance +14, Persuasion +9
Resistances - Cold, Thunder
Senses - Darkvision 60ft., passive Perception 12
Languages - Common, Primordial (Aquan)
Challenge - 11
Proficiency Bonus - +4
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Traits

Amphibious - The merfolk can breathe air and water.

Songs of the Sea - While singing (no action required), the Prima Donna emits a 60-foot Emanation. All allies within the Emanation add 1d4 to all Ability Checks, Attack Rolls, and Saving Throws. 
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Actions

Multiattack - The Prima Donna makes two High Note attacks. 

High Note - Melee or Ranged Attack Roll: +9, reach 5 ft. or range 60 ft. Hit: 27 (4d10 + 5) Thunder damage and the target has Disadvantage on their next Attack Roll. 

Cacophonous Chorus (Recharge 5-6) - The Prima Donna sings out a shrill, discordant, note causing all enemies within 60-feet to make a DC17 Wisdom Saving Throw. Failure: 28 (8d6) Psychic damage and the creature must use its Reaction to immediately move its full speed away from the Prima Donna. Success: Half damage and the creature does not have to move. 

Spellcasting - The Prima Donna casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 17):

At Will: Prestidigitation, Dancing Lights, Message, Charm Person, Disguise Self, Faerie Fire, Mirror Image, Suggestion, Wall of Water

2/day each: Major Image, Silence, Shatter (Level 7 Version)

1/day each: Greater Invisibility, Summon Elemental (Level 9 Version), Dominate Monster, Mass Suggestion—
Bonus Actions

Misty Step (3/Day) - The Prima Donna casts Misty Step, using the same spellcasting ability as Spellcasting. While underwater, the Prima Donna ignores the 3/Day limit. 

Song of Unraveling - As a Bonus Action, the Prima Donna infuses her song with disruptive magic for 1 minute. When attempting to cast a spell, any enemies within the Song of the Sea Emanation must make a DC17 Constitution Saving Throw or have their spell countered, per Counterspell. The Prima Donna can only infuse her Song of the Sea with one magical effect at a time. This effect ends immediately if Song of Aid or Song of Battle are used. 

Song of Aid - As a Bonus Action, the Prima Donna infuses her song with fortifying magic for 1 minute. At the start of their turns, each ally within the Song of the Sea Emanation are healed for 12 (3d4 + 5) Hit Points. If the creature is at full health, they gain half as many Temporary Hit Points instead. The Prima Donna can only infuse her Song of the Sea with one magical effect at a time. This effect ends immediately if Song of Unraveling or Song of Battle are used. 

Song of Battle - As a Bonus Action, the Prima Donna infuses her song with elemental thunder for 1 minute. Each ally within the Song of the Sea Emanation gains Resistance to Thunder damage and adds 1d8 Thunder damage to all of their attacks. The Prima Donna can only infuse her Song of the Sea with one magical effect at a time. This effect ends immediately if Song of Unraveling or Song of Aid are used.