Ikuchi

Ikuchi Oil. The ikuchi constantly emits a thick, nonflammable, yellowish oil. When the ikuchi is underwater, this oil makes the water within 30 feet of the ikuchi difficult terrain. Each time a creature moves more than 10 feet through this area it must succeed on a DC 15 Strength saving throw or be restrained by the thick oil until the end of its next turn. A creature under the effects of a freedom of movement spell or similar magic is immune to the effects of Ikuchi Oil.

Water Breathing. The ikuchi can breathe only underwater.

Multiattack. The ikuchi makes two attacks: one with its bite and one to constrict.

Bite. Melee Weapon Attack: +8 to hit, reach 15 ft., one target. Hit: 16 (2d10 + 5) piercing damage.

Constrict. Melee Weapon Attack: +8 to hit, reach 20 ft., one Huge or smaller creature. Hit: 14 (2d8 + 5) bludgeoning damage. The target is grappled (escape DC 16) if the ikuchi isn't already constricting two other creatures. Until this grapple ends, the target is restrained.

Crush (Recharge 4-6). Each creature grappled by the ikuchi must make a DC 16 Strength saving throw, taking 23 (4d8 + 5) bludgeoning damage on a failed save, or half as much damage on a successful one.