Beholder Crab

Antimagic Cone. 

The beholder crab's central eye creates an area of antimagic, as in the antimagic field spell, in a 150-foot cone. At the start of each of its turns, the beholder crab decides which way the cone faces and whether the cone is active. The area works against the beholder crab's own eye rays.

Amphibious. 

The crab can breathe air and water.

Bite. 

Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 19 (4d6+5) piercing damage.

Claw. 

Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 27 (4d10 + 5) bludgeoning damage, and the target is grappled, escape DC 15. The beholder crab has two claws, each of which can grapple only one target.

Eye Rays. 

The beholder crab shoots three of the following magical eye 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 17 Wisdom saving throw or be charmed by the beholder crab for 1 hour, or until the beholder crab harms the creature.

• 2. Paralyzing Ray. The targeted creature must succeed on a DC 17 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

• 3. Fear Ray. The targeted creature must succeed on a DC 17 Wisdom saving throw or be frightened for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

• 4. Disintegration Ray. If the target is a creature, it must succeed on a DC 17 Dexterity saving throw or take 45 (10d8) force damage. If this damage reduces the creature to 0 hit points, its body becomes a pile of fine gray dust.If the target is a Large or smaller nonmagical object or creation of magical force, it is disintegrated without a saving throw. If the target is a Huge or larger object or creation of magical force, this ray disintegrates a 10-foot cube of it.

• 5. Death Ray. The targeted creature must succeed on a DC 17 Dexterity saving throw or take 55 (10d10) necrotic damage. The target dies if the ray reduces it to 0 hit points.

• 6. Carcanisation Ray. The targeted creature must succeed on a DC 17 Charisma saving throw or be transformed into a giant crab, using everything but the mental scores of the giant crab statblock as if under the effect of a polymorph spell. While under the effects of this ray, the target is charmed by the beholder crab and follows any orders it gives to the best of their ability. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If the beholder crab is knocked unconscious or killed, this effect is lifted on any targets.