Cataken

Amphibious: The Cataken can breathe air and water.

Freedom of Movement: The Cataken ignores Difficult Terrain, and magical effects can't reduce its speed or cause it to be Restrained. It can spend 5 feet of Movement to escape from nonmagical restraints or being Grappled.

Siege Monster: The Cataken deals double damage to objects and structures.

• Multiattack. The Cataken makes three paw attacks, each of which it can replace with one use of Fling.

• Bite. Melee Weapon Attack: +17 to hit, reach 5 ft., one target. Hit: (3d8 + 10) piercing damage. If the target is a Large or smaller creature grappled by the Cataken, that creature is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the Cataken, and it takes 42 (12d6) acid damage at the start of each of the Cataken's turns. If the Cataken takes 50 damage or more on a single turn from a creature inside it, the Catken must succeed on a DC 25 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the Cataken. If the Cataken dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 15 feet of movement, exiting prone.

• Paw. Melee Weapon Attack: +17 to hit, reach 30 ft., one target. Hit: (4d6 + 15) bludgeoning damage. The target is grappled (escape dc 18) Until this grapple ends, the target is restrained. The Cataken has 2 paws, each of which can grapple one target.

• Fling. One Large or smaller object held or creature grappled by the Cataken is thrown up to 60 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 18 Dexterity saving throw or take the same damage and be knocked prone.

• Meow. The Cataken magically creates loud shrieks coming from its mouth,  which can strike a target the Cataken can see within 120 feet of it. A target must make a DC 23 Wisdom saving throw, taking 25 (4d10) Thunder damage on a failed save, or half as much damage on a successful one.

Can take 3 Legendary Actions, choosing from the options below. Only one legendary action can be used at a time, and only at the end of another creature's turn. Spent legendary Actions are regained at the start of each turn.

Paw Attack or Fling: The Cataken makes one Paw Attack or uses its Fling.

Meow (Costs 2 Actions): The Cataken uses Meow.

Throwup (Costs 3 Actions): The Cataken expels a cloud of throwup in a 60-foot radius. The cloud spreads around corners, and that area is heavily obscured to creatures other than the Cataken. Each creature other than the Cataken that ends its turn there must succeed on a DC 23 Constitution saving throw, taking 16 (3d10) poison damage on a failed save, or half as much damage on a successful one. A strong current disperses the cloud, which otherwise disappears at the end of the Cataken's next turn. Anyone in the Catakan swallowed will come out taking (2D4) acid damage.