Insatiable Brood

Aberrant Resilience. The insatiable brood has advantage on saves against spells or effects that would alter its form.

Magic Bites. The insatiable brood's Bites attacks are magical.

Siege Monster. The insatiable brood deals double damage to objects and structures.

Swarm. The insatiable brood can occupy another creature's space and vice versa, and the brood can move through any opening large enough for a Tiny creature. The brood can't regain HP or gain temporary HP.

Swarm Resilience. The swarm is resistant to bludgeoning, piercing, and slashing damage, and it is immune to the charmed, frightened, grappled, paralyzed, petrified, prone, restrained, and stunned conditions.

Void Dweller. The insatiable brood doesn't require air, food, drink, or sleep, and it is immune to the effects of Void terrain. In addition, it can fly through the Void as if through air.

Bites. _Melee Weapon Attack:_ +5 to hit, reach 0 ft., one creature in the swarm's space. _Hit:_ 14 (4d6) piercing damage plus 18 (4d8) force damage, or 7 (2d6) piercing damage plus 9 (2d8) force damage if the insatiable brood has half its HP or fewer.

Void Gaze. The insatiable brood turns all its individual heads in one direction, and its hundreds of Void-filled eyes stare at one creature the brood can see within 30 feet of it. The target must succeed on a DC 13 WIS save or be frightened until the end of its next turn. If the target fails the save by 5 or more, it suffers a random, short-term dread effect for 1 minute.