Akantor

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

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

Multiattack. The akantor makes three attacks, one with its bite, one with its claw and one with its tail.

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 30 (4d10 + 8) piercing damage. If the target is a creature, it is grappled (escape DC 22) . Until this grapple ends, the target is restrained, and the akantor can't bite another target.

Claw. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 14 (2d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 20 ft., one target. Hit: 26 (4d8 + 8) bludgeoning damage.

Sonic Blast (Recharge 5-6). exhales a blast of air in a 120-foot line that is 10 feet wide. The blast destroys all terrain and structures, magic or otherwise, within its path. Each creature in that line must make a DC 21 Dexterity saving throw, taking 45 (13d6) force damage on a failed save, or half as much damage on a successful one.

Crush. If the akantor uses all of its movement to rise up on its hind legs. It can then use its action to slams its body in an area within 20 feet of its location that contains one or more other creatures. Each of those creatures must succeed on a DC 23 Strength or Dexterity saving throw (target's choice) or be knocked prone and take 22 (4d6 + 8) bludgeoning damage + 22 (4d6 + 8) fire damage. On a successful save, the creature takes only half the damage, isn't knocked prone, and is pushed 5 feet out of the akantor's space into an unoccupied space of the creature's choice. If no unoccupied space is with in range, the creature instead falls prone in the akantor's space.

Swallow. The akantor makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite damage, the target 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 akantor, and it takes 21 (6d6) acid damage at the start of each of the akantor's turns. 
If the akantor takes 50 damage or more on a single turn from a creature inside it, the akantor must succeed on a DC 22 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 akantor. If the akantor dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.

The akantor can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creatures turn. The akantor regains spent legendary actions at the start of its turn.

Dig. The akantor burrows underground and move up to its burrow movement.

Detect. The akantor makes a Wisdom (Perception) Check.

Chomp (Costs 2 Actions). The akantor makes one bite attack or uses its Swallow.