Symphony Master (5e Creature)

ACTIONS

Multiattack. The symphony master casts a spell with a casting time of 1 action and makes one attack with its baton shuriken. When its Concerto is available, it can use it in place of the spell.

Spellcasting. The symphony master is a 10th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 17, +9 to hit with spell attacks). The symphony master has the following spells prepared:

Cantrips (at will): eldritch blast, guidance, vicious mockery
1st level (4 slots): charm person, chromatic orb, cure wounds, healing word, hex, mage armor, magic missile
2nd level (3 slots): aid, hold person, misty step, moonbeam, shatter, silence
3rd level (3 slots): bestow curse, counterspell, dispel magic, fear, haste, spirit guardians
4th level (2 slots): banishment, charm monster, confusion, dominate beast
5th level (2 slots): dominate person, geas, hold monster, wall of force

Baton Shrunken. Ranged Spell Attack: +9 to hit, range 120 ft., one target. Hit: 15 (2d10 + 4) piercing damage.

Concerto (Recharge 6). The symphony master magically plays one of its instruments:

Fortissimo Blast. The symphony master fires a massive sound wave from its trumpet. Each creature within 60 feet of the symphony master must make a DC 17 Strength saving throw. On a failed save, the creature takes 36 (8d8) thunder damage and is pushed 20 feet away from the symphony master and knocked prone. On a successful save, the creature takes half as much damage and isn't pushed or knocked prone.
Hell's Melody. The symphony master plays a tune from its violin. Each creature within 30 feet of the symphony master that can hear it must succeed on a DC 17 Wisdom saving throw or be cursed by the symphony master for 1 minute. While cursed, the creature takes 9 (2d8) necrotic damage at the start of each of their turns and the target's hit point maximum is reduced by an amount equal to the necrotic damage taken. The reduction lasts until the target finishes a long rest or is subjected to the greater restoration spell or other magic. The target dies if this effect reduces their hit point maximum to 0.
'Beat Impact.' The symphony master sends forth three sound waves from its drums at different points it can see within 60 feet of it. Each creature in a 20-foot-radius sphere centered on one of those points must make a DC 17 Constitution saving throw, taking 45 (10d8) thunder damage on a failed save, or half as much damage on a successful one. A creature in the area of more than one sound wave is affected only once.