Broholder

Cone of Slow. The broholder's central eye creates an area of lethargy, as in the slow spell, in a 150-foot-cone. At the start of each of its turns, the beholder decides which way the cone faces and whether the cone is active.

Legendary Resistance (3/Day). If the broholder fails a saving throw, it can choose to succeed instead.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 18 (4d6+4) piercing damage.

Rave Rays. The broholder shoots three of the following magical rave rays at random (reroll duplicates), choosing one to three targets it can see within 120 feet of it:

1. Charm Ray. The targeted creature must succeed on a DC 16 Wisdom saving throw or be charmed by the broholder for 1 hour, or until the broholder harms the creature.
2. Laughing Ray. The targeted creature must succeed on a DC 16 Wisdom saving throw or fall prone laughing, becoming incapacitated and unable to stand up for the duration. At the end of each of its turns, and each time it takes damage, the target can make another Wisdom saving throw. The target has advantage on the saving throw if it's triggered by damage. On a success, the effect ends.
3. Hypnotic Ray. The targeted creature must succeed on a DC 16 Wisdom saving throw or be charmed for 1 minute. While charmed by this spell, the creature is incapacitated and has a speed of 0. The effect ends for an affected creature if it takes any damage or if someone else uses an action to shake the creature out of its stupor.
4. Sickening Ray. The targeted creature must succeed on a DC 16 Wisdom saving throw. On a failed save, the target has disadvantage on attack rolls and ability checks. At the end of each of its turns, it can make another Wisdom saving throw. If it succeeds, the effect ends.
5. Static Ray. The targeted creature must make a DC 16 Dexterity saving throw, taking 28 (8d6) psychic damage on a failed save, or half as much damage on a successful one. Also on a failure, the target has muddled thoughts for 1 minute, subtracting a d6 from every attack roll and ability check as well as Constitution saving throws to maintain concentration on spells. The target can make a DC 16 Intelligence saving throw at the end of each of their turns to end this effect.
6. Enfeeblement Ray. The target must make a DC 16 Dexterity saving throw or become enfeebled. For the next minute, the target deals only half damage with weapon attacks that use Strength. The target can attempt a DC 16 Constitution saving throw at the end of each of its turns to end this effect. 
7. Rohypnol Ray. The targeted creature must succeed on a DC 16 Wisdom saving throw or fall asleep and remain unconscious for 1 minute. The target awakens if it takes damage or another creature takes an action to wake it. This ray has no effect on constructs and undead.
8. Dance Ray. The targeted creature must make a DC 16 Wisdom saving throw. On a failed save, the target begins a comic dance in place: shuffling, tapping its feet, and capering for the duration. Creatures that can't be charmed are immune to this ray. 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 ray, other creatures have advantage on attack rolls against it. As an action, a dancing creature makes a DC 16 Wisdom saving throw to regain control of itself. On a successful save, the spell ends.
9. Chain Lightning Ray. The target must succeed on a DC 16 Dexterity saving throw or take 27 (6d8) lightning damage. This lightning ray then jumps to two other targets within 30 ft who must make a DC 16 Dexterity saving throw or take the lightning damage as well.
10. Dumb Ray. The targeted takes 4d6 psychic damage and must make a DC 16 Intelligence saving throw. On a failed save, the creature's Intelligence and Charisma scores become 1. The creature can't cast spells, activate magic items, understand language, or communicate in any intelligible way. The creature can, however, identify its friends, follow them, and even protect them. The target creature can attempt the save again at the end of each of its turns.

The broholder can take 3 legendary actions, using the Rave Ray option below. It can take only one legendary action at a time and only at the end of another creature’s turn. The broholder regains spent legendary actions at the start of its turn.

Rave Ray. The broholder uses one random rave ray.