Sinstar

Legendary Resistance (3/Day). Choose to succeed failed save.

Spiny Defense. A creature that touches the sinstar or hits it with melee attack while within 5 ft. of it takes 10 (3d6) piercing damage and if the target is a Humanoid it must make DC 19 Con save or contract the thrall sickness disease (see the Thrall Sickness trait).

Thrall Sickness. A Humanoid infected with this disease manifests symptoms 1d4 days after infection which include excessive thirst increased desire for exposure to sunlight and the appearance of itchy bumps on the skin. This disease wears down the victim's psyche while slowly transforming its body. Until the disease is cured at the end of each long rest the infected creature must make a DC 19 Con save. On a failure the creature's Dex and Int scores are each reduced by 1d4. The reductions last until the infected creature finishes a long rest after the disease is cured. The infected creature dies if the disease reduces its Dex or Int score to 0. A Humanoid that dies from this disease transforms into a star thrall under the complete psychic control of the sinstar that infected it. This otherworldly disease can be removed by the greater restoration spell or similar magic.

Multiattack. Alluring Whispers then three Spines or Psychic Lash attacks.

Spines. Melee or Ranged Weapon Attack: +8 to hit 5 ft. or range 20/60' one target 16 (4d6+2) piercing damage and if the target is a Humanoid it must make DC 19 Con save or contract the thrall sickness disease (see the Thrall Sickness trait).

Psychic Lash. Ranged Spell Attack: +11 to hit, 120 ft., one target, 18 (3d8+5) psychic.

Alluring Whispers. The sinstar telepathically whispers soothing and beckoning words in the minds of all Humanoids within 120' of it. Each target must make DC 19 Wis save or be charmed for 1 min. While charmed a creature is incapacitated and if it is more than 5 ft. away from the sinstar it must move on its turn toward the sinstar by the most direct route trying to get within 5 ft. of the sinstar and touch it. The creature doesn't avoid opportunity attacks but before moving into damaging terrain such as lava or a pit and whenever it takes damage from a source other than the sinstar the creature can repeat the save. A charmed creature can also re-save at end of each of its turns. If the save is successful the effect ends on it. A creature that successfully saves is immune to this sinstar's Alluring Whispers for the next 24 hrs.

Spines. Makes one Spines attack.

Teleport. Magically teleports up to 120' to an unoccupied spot it sees.

Detonate Thrall (2). Orders one of its star thralls to explode. Each creature within 10 ft. of the thrall must make a DC 19 Dex save taking 10 (3d6) bludgeoning damage and 7 (2d6) piercing damage on a failed save or half damage if made.