Amphibious. The Titan Crab can breathe air and water.

Claw. Melee Weapon Attack: +8 to hit, reach 15 ft., one target. Hit: 33 (5d10 + 4) bludgeoning damage. On a hit, the target creature must also make a grapple check (DC 15), and be grappled and restrained on a failed save.

Squeeze. When a creature has been grappled, the Titan Crab can use its action to squeeze them, dealing 27 (4d10 + 4) bludgeoning damage, and the target must make a DC 13 constitution saving throw. On a fail, they gain a level of exhaustion.

Boulder. Ranged Weapon Attack: +6 to hit, range 40/100 ft., 1 target. Hit: 20 (4d8 + 1) bludgeoning damage, as the Titan Crab picks up a large rock or small boulder.

The Titan Crab has 3 legendary actions, and regains these uses after a long rest.

Legendary Shell (Costs 1 Actions). The Titan Crab surges legendary energy through its shell as a reaction. Any spell that hits it will either be absorbed or deflected.

Claw (Costs 1 Actions). The Titan Crab makes another claw attack.