Annoying Buzzing Cone.  As long as its movement speed is greater than 0 and it does not have the Incapacitated condition, the beeholder emits an annoying buzz in a 150-feet cone. Within that area, creatures have the Deafened condition, cannot concentrate and spells with Verbal components cannot be cast. At the start of each of its turns, the beeholder decides which way the cone faces and whether the cone is active.

Eyestalks. When the beeholder takes a critical hit, it must succeed on a Constitution saving throw with a DC equal to the damage taken or lose an eyestalk, and with it, lose the use of a random eye ray. After one minute, the severed eyestalk regrows.

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

Magic Resistence. The beeholder has advantage on saving throws against spells and magical effects.

Compound-Eyed Menace. The beeholder can see through the eyes of any creature within 5 miles of it, unless such a creature is protected by a  mind blank spell or similar magic.

Sovereign of the Swarm. All bees within 5 miles of the beeholder have the Charmed condition, have advantage on attack rolls and follow the beeholder's commands. This effect only ends when the beeholder dies.

Sticky Mess. If a creature touches the beeholder, it must succeed on a DC 18 Strength saving throw or gain the Grappled and Restrained. If a creature hits the beeholder with a melee weapon attack, it must succeed on a DC 18 Strength saving throw or its weapon is stuck to the beeholder.
A creature can free itself or a stuck weapon by using its action to make a DC 18 Strength (Athletics) check. Alternatively, a creature can free itself or a weapon by using its action or bonus action to lick up all the honey restraining it; in this case it gains a level of Exhaustion.
If the beeholder takes fire damage, stuck creatures and weapons are freed and this trait does not function until the end of the beeholder's next turn.

Multiattack. The beeholder can use its Sweet, Sweet Honey. It then makes an attack with its Stinger and uses its eye rays.

Stinger. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit:  11 (2d4+6) piercing damage and the target must make a DC 18 Constitution saving throw. On a failure, it takes 54 (12d8) poison damage and is under the effect of a power word pain spell until the end of its next turn. 

Sweet, Sweet Honey. The beeholder creates an irresistable scent of sweet, sweet honey. Each creature of the beeholder's choice within 120 feet of it must succeed on a Wisdom saving throw or have the Charmed condition.

While charmed in this way, a creature uses all its movement on its turn to approach the beeholder. If it starts its turn within 5 feet of the beeholder, it uses all its movement and its action to lick up as much honey as possible, gaining a level of Exhaustion for each turn it does so.

An affected creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the beeholder's Sweet, Sweet Honey for the next 24 hours.

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

• 1. Swarming Ray.  A swarm of bees (use the swarm of insects statblock) appears in the target's space. The swarm moves with the target and takes its turn after the target's turn. If there are three or more swarms in a creature's space, that creature has the Blinded and its movement speed is halved.
  
• 2. Ray of To Bee or Not To Bee. The target rolls any die. On an even number, it is polymorphed into a large bee (use the giant wasp statblock) until the end of its next turn. While a bee, it is Charmed by the beeholder and follows its commands. On an odd number, the target feels its existence coming to an end and must succeed on a DC 18 Constitution saving throw, taking 54 (12d8) necrotic damage on a failure or half as much on a success.
  
• 3. Honey Assault Ray. The targeted creature must succeed on a DC 18 Dexterity saving throw or take 18 (4d8) bludgeoning damage and have the Prone and Restrained condition.  A creature restrained in this way can use its action to attempt to escape by succeeding on a DC 18 Strength (Athletics) check. If a creature restrained in this way takes fire damage, it has advantage on this check. Alternatively, a creature can free itself by using its action or bonus action to lick up all the honey restraining it; in this case it gains a level of Exhaustion.
  
• 4. Ray of Beefuddlement. The targeted creature must make a DC 18 Wisdom saving throw. On a failure, it believes of itself to be a bee. It is unable to cast spells and can only use weapons that deal piercing damage. Moreover, whenever it tries to speak, it only creates a buzzing sound. A creature can repeat the saving throw at the end of each of its turns, ending the effect on a success.
• 5. Ray of Beewilderment. The target must succeed on a DC 18 Intelligence saving throw or is under the effect of an enemies abound spell until the end of its next turn.
• 6. Buzzkill Ray. The targeted creature must succeed on a DC 18 Constitution saving throw or take 28 (6d8) thunder damage and 26 (6d8) necrotic damage.
• 7. Jarring Ray. The target must succeed on a DC 18 Dexterity saving throw. On a failure, it is enclosed by an empty jar of honey until the end of its next turn. The jar acts like a wall of force spell, but can be attacked. It is an object with 60 hit points, an AC of 20,  immunity to poison and psychic damage and vulnerable to bludgeoning and thunder damage.
• 8. Sting Ray. The target must succed on a DC 18 Dexterity saving throw, taking 36 (8d8) piercing damage on a failure or half as much on a success. In addition, on a failure, the target has the Paralyzed condition until the end of its next turn.
• 9. Ray of Bee-auty. The target is compelled to find out what is in the eye of the beeholder. It must make a DC 18 Wisdom (Perception) check. On a success, it realizes there is nothing worthwile to see, because this is not a beholder. On a failure, it gains the Incapacitated condition until the end of its next turn as it carefully examines the beeholder's eye in search of beauty. While incapacitated in this way, attack rolls have advantage against the target.
• 10. Bee-lzebub Ray. The target must succeed on a DC 18 Wisdom saving throw or take 21 (6d6) psychic damage and be frightened of the beeholder until the end of its next turn.

The beeholder can take a total of two reactions, but only one per turn.

Buzz off!. Trigger: A creature hits the beeholder with an attack. Effect: The creature must immediately use its reaction, if available, to move as far away from the beeholder as it can, using the safest route.

Eye for Eye. Trigger: A creature scores a critical hit against the beeholder and successfully severs one of its eyestalks. Effect: The beeholder immediately uses two eye rays against that creature and, if the creature is within reach, makes a Stinger attack.

Sovereign's Command. Trigger: A creature damages the beeholder or any bee within 120 feet of the beeholder. Effect:  Any bee and any swarm under the beeholder's command can use its reaction to make an attack.

Gathering Swarm (1/day). Trigger: The beeholder drops below a third of its HP (below 95) for the first time. Effect:  From now on, the beeholder can use its Legendary Actions. In addition, the area within 20 feet of the beeholder is now considered under the effect of an insect plague spell. The effect ends after an hour or when the beeholder dies.

Once it has used its Gathering Swarm reaction, the beeholder can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The beeholder regains spent legendary actions at the start of its turn.

Attack Order. Melee Weapon Attack: +11 to hit, reach 120 feet, one target. Hit:  26 (8d4+6) piercing damage. The beeholder orders its swarm to attack.

Defend Order. The next time the beeholder takes damage from an attack or spell, it can reduce the damage by 27 (1d10+22). The beeholder orders its swarm to defend it by taking damage for it.

Heal Order. The beeholder regains 26 (8d4+6) hit points and is cured of any debilitating condition. The beeholder is healed by loyal worker bees.