Chasmfiend

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

Mandra Bond. The chasmfiend’s bonded mandras reduce the effect of gravity on its body. The chasmfiend ignores difficult terrain, can climb vertical surfaces without checks, takes no falling damage, and cannot be knocked prone unless incapacitated.

Stone Shell. The chasmfiend’s armored carapace protects it from attacks directed at its upper body and flanks. The chasmfiend has resistance to bludgeoning, piercing, and slashing damage from attacks that do not specifically target a weak point such as its underside, joints, eyes, or mouth. An attacker can target a weak point by attacking with disadvantage. Attacks made with weapons designed to pierce or cut stone (such as Shardblades) ignore this resistance.

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

Burst Predator. If the chasmfiend moves at least 30 feet straight toward a creature before hitting it with a claw attack, the attack deals an additional 18 (4d8) damage and the target must succeed on a DC 20 Strength save or fall prone. After using this trait, the chasmfiend’s speed is reduced by half until the end of its next turn.

Pupation. Chasmfiends try to find plateaus to pupate on. If a chasmfiend is found in a pupa, it will not attack until its pupa is completely destroyed, though it will still take damage normally.

Rhythmic Communication. The chasmfiend can communicate emotions, impressions, and simple concepts telepathically with other chasmfiends and singers within 300 feet. This communication cannot convey precise spoken language.

Multiattack. The chasmfiend can use its Frightful Presence. It then makes six attacks: one with its bite, four with its claws, and one with its tail. It can use its Swallow instead of its bite.

Bite. 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 chasmfiend can't bite another target.

Claw. Melee Weapon Attack: +19 to hit, reach 15ft., one target. Hit: 28 (4d8 + 10) slashing damage. If the target is Huge or smaller, it must succeed on a DC 20 Strength saving throw or be pushed 15 feet.

Tail. Melee Weapon Attack: +19 to hit, reach 20ft., one target. Hit: 24 (4d6 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be knocked prone.

Frightful Presence. Each creature within 120 feet of the chasmfiend and aware of it must succeed on a DC 20 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 chasmfiend 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 chasmfiend's Frightful Presence for the next 24 hours.

Swallow. The chasmfiend makes one bite attack against a Large or smaller creature it is grappling. If the attack hits, the target takes the bite's damage, the target is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, but any attacks made against the chasmfiend deal double damage. It also has total cover against attacks and other effects outside the chasmfiend, and it takes 56 (16d6) acid damage at the start of each of the chasmfiend's turns.

If the chasmfiend takes 60 damage or more on a single turn from a creature inside it, the chasmfiend must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the chasmfiend. If the chasmfiend dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 30 feet of movement, exiting prone.

The chasmfiend 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 chasmfiend regains spent legendary actions at the start of its turn.

Attack. The chasmfiend makes one claw attack or tail attack.

Move. The chasmfiend moves up to half its speed.

Chomp (Costs 2 Actions). The chasmfiend makes one bite attack or uses its Swallow.