Zilbrosh unlocks his abilities as it’s connection with it’s wizard partner grows stronger. When its wizard partner reaches levels 5, 10, 13, and 16, roll a d20. On a 10 or higher, Zilbrosh gains back one eyestalk ability, gained in order of 1 to 4. If you roll 1-9, that ability can only be learned at the next milestone of you roll a 15 or higher. Abilities such as Bless, Guidance, and Luck can help toward recovering a missed ability, but cannot be used to attempt to gain the ability the first time.

Bite. Melee Weapon Attack: +1 to hit, reach 5 ft., one target. Hit: 2 (1d6 − 1) piercing damage.

Eye Rays. Zilbrosh can shoot one of the following magical eye rays at one creature it can see within 90 feet of it. It can use a ray only once per minute. Zilbrosh or it’s wizard can choose which one it uses, depending on how many are unlocked. Refer to Special Traits for more information. 

1. Charm Ray. The targeted creature must succeed on a DC 16 Wisdom saving throw or be charmed by the beholder for 1 hour, or until the beholder harms the creature.
2. Paralyzing Ray. The target must succeed on a DC 16 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 target must succeed on a DC 16 Wisdom saving throw or be frightened for 1 minute. The target can repeat the saving throw at the end of each of its turns, with disadvantage if the spectator is visible to the target, ending the effect on itself on a success.
4. Disintegration Ray. If the target is a creature, it must succeed on a DC 16 Dexterity saving throw or take 45 ([roll]10d8[/roll]) 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.

Hide: As a bonus action, Zilbrosh can hide.

Invisibility: If Zilbrosh is targeted by an attack, it can turn invisible. The attack now is at disadvantage, or if it is a spell attack, Zilbrosh gets advantage on the spell’s DC roll. It must remain invisible until the end of combat or 1 minute, whichever comes first, and Zilbrosh cannot attack or use eyestalk abilities.