Arcwhale, Adult

Siege Monster. The arcwhale deals double damage to airships, objects, and structures.

Multiattack. The arcwhale makes two attacks: one with its bite and one with its tail. It can't make both attacks against the same target.

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 33 (4d12 + 7) piercing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the Arcwhale can't bite another target.

Tail. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 20 (3d8 + 7) bludgeoning damage.

Swallow. The arcwhale makes one bite attack against a Medium or smaller target it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside the arcwhale, and it takes 10 (3d6) acid damage at the start of each of the arcwhale's turns. The arcwhale can have only one target swallowed at a time.
If the arcwhale dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.