Frightful Appearance. Each creature that is within 60 feet of the aberration and aware of it must succeed on a DC 15 Wisdom saving throw or become stunned for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success and becoming immune to this effect for the next 24 hours.

Amorphous. The aberration can move through a space as narrow as 6 inches wide without squeezing and is immune to both piercing and slashing damage.

Spider Climb. The aberration can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Regeneration. The aberration regains 10 hit points at the start of its turn. If the aberration  takes radiant damage, this trait doesn’t function at the start of the aberration’s next turn. The aberration dies only if it starts its turn with 0 hit points and doesn’t regenerate.

Hideous Grasp. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage plus 18 (4d8) necrotic damage. In addition, If the target is a creature, it must succeed on a DC 14 Constitution saving throw or inflicted with a foul disease. The diseased target can't regain hit points, and its hit point maximum decreases by 10 (3d6) for every 24 hours that elapse. If the disease reduces the target's hit point maximum to 0, the target dies, and its body becomes a putrid, festering corpse.

Split. When an aberration that is Medium or larger is subjected to force or slashing damage, it splits into two new aberrations if it has at least 10 hit points. Each new aberration has hit points equal to half the original aberration's, rounded down. New aberrations are one size smaller than the original aberration.