Creature Sense. The neothelid is aware of the presence of creatures within 1 mile of it that have an Intelligence score of 4 or higher. It knows the distance and direction to each creature, as well as each creature’s Intelligence score, but can’t sense anything else about it. A creature protected by a mind blank spell, a nondetection spell, or similar magic can’t be perceived in this manner.

Innate Spellcasting (Psionics). The neothelid’s innate spellcasting ability is Wisdom (spell save DC 13). It can innately cast the following spells, requiring no components:

At will: levitate

Magic Resistance. The neothelid has advantage on saving throws against spells and other magical effects.

Tentacles. Melee Weapon Attack: +7 to hit, reach 40 ft., one creature. Hit: 8 (1d8 + 4) bludgeoning damage plus 4 (1d8) psychic damage. If the target is a Small or smaller creature, it must succeed on a DC 14 Strength saving throw or be swallowed by the neothelid. A swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the neothelid, and it takes 21 (6d6) acid damage at the start of each of the neothelid's turns.

 If the neothelid takes 10 damage or more on a single turn from a creature inside it, the neothelid must succeed on a DC 13 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 5 feet of the neothelid. If the neothelid dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 10 feet of movement, exiting prone.

Acid Breath (Recharge 5-6). The neothelid exhales acid in a 30-foot cone. Each creature in that area must make a DC 14 Dexterity saving throw, taking 21 (6d6) acid damage on a failed save, or half as much damage on a successful one.