Crabzilla (king crab)

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

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

Reflective Carapace. Any time the crabzilla is targeted by a magic missile spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, the crabzilla is unaffected. On a 6, the crabzilla is unaffected, and the effect is reflected back at the caster as though it originated from the crabzilla , turning the caster into the target.

Siege Monster. The crabzilla deals double damage to objects and structures.

Multiattack. The crabzilla can use its Frightful Presence. It then makes five attacks: one with its grab, two with its claws, and two with its Lasers. It can use its crush instead of its grab.

Grab. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 36 (4d12 + 10) piercing damage. If the target is a creature, it is grappled (escape DC 20). Until this grapple ends, the target is restrained, and the crabzilla can’t grab another target.

Claw. Melee Weapon Attack: +19 to hit, reach 15ft., one target. Hit: 28 (4d8 + 10) slashing damage.

Laser. Melee Weapon Attack: +19 to hit, reach 10ft., one target. Hit: 15 (1d10 + 10) radiant damage plus 16 (3d10) fire damage.

Frightful Presence. Each creature of the crabzilla's choice within 120 feet of it and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, with disadvantage if the crabzilla is within line of sight, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the crabzilla's Frightful Presence for the next 24 hours.

Crush. The crabzilla makes one grab attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the Grab's damage,and the target is crushed. While crushed, the creature is grappled and restrained, it has half cover against attacks and other effects outside the tarrasque, and it takes 56 (16d6) bludgeoning damage at the start of each of the crabzilla's turns. The target can escape with a successful DC 20 dexterity(acrobatics) or strength(athletics) check exiting prone.

Summon crabs. The crabzilla summons crabs. 4d4 swarms of crabs emerge from the ground within 60 ft. of crabzilla. The summoned crabs are friendly to crabzilla. The crabs remain for 1 hour, until the summoner dies, or they are dismissed by the summoner as a bonus action.

The crabzilla 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 creature’s turn. The crabzilla regains spent legendary actions at the start of its turn.

Attack. The crabzilla makes one claw attack or laser attack.

Lunge. The crabzilla moves up to half its speed.

Snatch(Costs 2 Actions). The crabzilla makes one grab attack or uses its crush.