Royal Carapace. The Mirelurk Queen has resistance to nonmagical bludgeoning, piercing, and slashing damage. When she takes a critical hit, she can reduce the damage by half (no action required). This trait can be used once per round.

Amphibious Tyrant. The Mirelurk Queen can breathe air and water. While submerged or partially submerged in water, she has advantage on Strength checks and saving throws.

Broodmother. At the start of combat, the Mirelurk Queen is accompanied by 2 mirelurks. While at least one hatchling is alive, the Queen has advantage on Wisdom saving throws.

Multiattack. The Mirelurk Queen makes three attacks: two with her Claws and one with her Bite, or one Corrosive Spray.

Claw. Melee Weapon Attack: +12 to hit, reach 10 ft., one target.
Hit: 18 (2d10+7) slashing damage, and the target must succeed on a DC 18 strength saving throw or be knocked prone.

Bite. Melee Weapon Attack: +12 to hit, reach 5 ft., one target.
Hit: 26 (3d12+7) piercing damage.

Corrosive Spray (Recharge 5–6). The Mirelurk Queen spews acid in a30-foot cone.  Creatures in the area must make a DC 18 dexterity savong throw, taking 45 (10d8) acid damage on a failed save, or half as much on a success.
The affected area becomes acid-slick terrain until the end of the Queen’s next turn. Creatures that start their turn in the area take 10 (3d6) acid damage.

Spawn the Brood (Recharge 6). The Mirelurk Queen summons 2d4 mirelurks in unoccupied spaces within 20 feet of her. Hatchlings act immediately after her turn.

The Mirelurk Queen 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. She regains spent legendary actions at the start of her turn.

Claw Snap. (1 Action) The Mirelurk Queen makes one Claw attack

Brood Surge (2 Action). One Mirelurk Hatchling within 30 feet can: Move up to its speed, Make one attack.

Royal Bellow. (3 Actions) The Mirelurk Queen unleashes a thunderous bellow. Each enemy of her choice within 30 feet must succeed on a DC 16 Wisdom saving throw or be frightened until the end of their next turn. Mirelurks have advantage on attack rolls against frightened creatures.