Actions

Multiattack. The chasm fiend makes four attacks. Two with its claws, only one of the other attacks can be a slam.   Bite. Melee Weapon Attack: 1d20+11 to hit, reach 5ft., one target. Hit: 28 4d10+6 bludgeoning damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be grappled. Until this grapple ends, the chasm fiend can't use its bite against another target.   Claws. Melee Weapon Attack: 1d20+11 to hit, reach 20ft., one target. Hit: 24 4d8+6 piercing damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be grappled. The chasm fiend may grapple up to four creatures with its claws. Until one of the grapples end, the chasm fiend can not use that claw against another target.   Slam. Melee Weapon Attack: 1d20+11 to hit, reach 20ft., one target. Hit: 39 6d10+6 bludgeoning damage.   Tail. Melee Weapon Attack: 1d20+11 to hit, reach 15ft., one target. Hit: 24 4d8+6 bludgeoning damage.   Claw Pinch. The chasm fiend pinches an object it is holding or a creature it is grappling in its claws. The target must succeed a DC 18 Str save or take 54 12d8 piercing damage.   Swallow. The chasm fiend makes one bite attack against a Medium or smaller creature it is grappling. If the attack hits, that creature takes the bite's damage and 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 chasm fiend, and it takes 21 6d6 acid damage at the start of each of the chasm fiend's turns.