Armor Class 17 (natural armor)
Hit Points 114 (12d10 + 48)
Speed 25 ft., climb 25 ft.
Saving Throws CON +8
Skills Perception +6
Condition Immunities blinded
Senses blindsight 500 ft. (blind beyond this radius), passive Perception 16
Languages understands Deep Speech, telepathy 1 mile
Challenge 11
Legendary Resistance (2/Day). If the balhannoth fails a saving throw, it can choose to succeed instead.
Multiattack. The balhannoth makes a bite attack and up to two tentacle attacks, or it makes up to four tentacle attacks.
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 25 (4d10 + 3) piercing damage.
Tentacle. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage, and the target is grappled (escape DC 15) and is moved up to 5 feet toward the balhannoth. Until this grapple ends, the target is restrained, and the balhannoth can't use this tentacle against other targets. The balhannoth has four tentacles.
Bite Attack. The balhannoth makes one bite attack against one creature it has grappled.
Teleport. The balhannoth magically teleports, along with any equipment it is wearing or carrying and any creatures it has grappled, up to 60 feet to an unoccupied space it can see.
Vanish. The balhannoth magically becomes invisible for up to 10 minutes or until immediately after it makes an attack roll.
Mordenkainen's Tome of Foes, p. 119