Multiattack

The star spawn can use disintegrating gaze if it's available, and also make one claws attack and one dimensional stomp attack.

Crushing Claws

Melee Weapon Attack. +12 to hit, reach 10 ft., one target. Hit: 20 (2d12 + 7) bludgeoning damage plus 13 (3d8) necrotic damage.

Disintegrating Gaze (Recharge 5-6)

Ranged Spell Attack: +15 to hit, range 60 ft., one target in line of sight. Hit: 32 (5d12) necrotic damage, and the target must make a successful DC 20 Constitution saving throw or dissipate into vapor as if affected by a gaseous form spell. An affected creature repeats the saving throw at the end of each of its turns; on a success, the effect ends on that creature, but on a failure, the creature takes another 32 (5d12) necrotic damage and remains gaseous. A creature reduced to 0 hit points by this necrotic damage is permanently disintegrated and can be restored only by a wish or comparable magic that doesn't require some portion of a corpse to work.

Dimensional Stomp

Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 18 (2d20 + 7) bludgeoning damage, and the target must make a successful DC 15 Dexterity saving throw or be teleported to a new location as if affected by the dimension door spell. The destination is chosen by the star spawn, but it cannot be in the same space as another object or creature.