Blessed of Kavrundoth

False Appearance. If the Blessed is motionless, has its eyes and mouth closed, and is prone at the start of combat, it has advantage on its initiative roll. Moreover, if a creature hasn’t observed the Blessed move or act, that creature must succeed on a DC 18 Intelligence (Investigation) check to discern that the Blessed is anything other than a large ocean rock.

Legendary Resistance (3/Day). If the Blessed fails a saving throw, it can choose to succeed instead.

Strange Nature. The Blessed has a natural advantage against saving throws caused by magic.

Weird Magic. As a reaction, the Blessed of Kavrundoth can cast counterspell, using Intelligence as its spellcasting ability.

Multiattack. The Blessed of Kavrundoth makes three attacks - one claw, and two blast. If close enough, it can also replace one of these attacks with a Bite attack.

Bite. Melee Weapon Attack: +9. Hit: 3d8+8 piercing damage plus 3d6 psychic damage. The target must also make a DC 15 Intelligence saving throw, or begin having hallucinations as determined by the DM.

Claw. Melee Weapon Attack: +9 to hit, reach 10 ft., one creature. Hit:  3d10+8 bludgeoning damage, and the target is grappled (escape DC 15). 

Blast. Melee or Ranged Weapon Attack: +6 to hit, reach 90 ft., one creature. Hit:  2d10 psychic damage.

Will of the Deep (recharge 4). The Blessed of Kavrundoth can force all creatures it can see within 60 feet to make an Intelligence saving throw. On a failure, they begin to hallucinate as determined by the DM. They immediately take 2d8 psychic damage, and are blinded by the effects of the hallucinations. At the beginning of subsequent turns, they take an additional 1d8 psychic damage. 

A creature can attempt the saving throw again at the end of each of its turns. If a creature fails the save by 5 or more, they become vulnerable to the next source of psychic damage it receives. If it succeeds, the effect ends. 

•  The Blessed of Kavrundoth focuses its psychic abilities on hindering those in its area. Choose one target within 60 feet of the Blessed. Until the end of their next turn, they have disadvantage on Intelligence saving throws.

• The Blessed chitters for it to be protected. Until initiative count 20 on the next round, whenever the Blessed is targeted by an attack, a drow within 5 feet of it can use its reaction to switch places with the Blessed, becoming the target of the attack instead.

• A supernatural chill spreads throughout the water of the lair. Each creature other than the Blessed of Kavrundoth within the lair must succeed a DC 15 Constitution saving throw or have their movement speed halved until the end of their next turn.