Black Worm (Dimensional Horror)

Keen Hearing and Smell The worm has advantage on Wisdom (Perception) checks that rely on hearing or smell.

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

Magic Resistance. The worm has Advantage on saving throws against spells and other magical effects.

Magic Weapons. The worm's weapon attacks are magical.

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

Silent Vulnerability. The worm cannot detect creatures under the effects of magical silence (e.g. silence spell) if they also remain still and make no sound. This renders such creatures effectively invisible to it.

Multiattack. The worm makes six attacks: six with its claws.

Bite. Melee Attack Roll: +19, reach 10 ft. Hit: 28 (4d8 + 10) Piercing damage, and the target has the Grappled condition (escape DC 20). Until the grapple ends, the target has the Restrained condition and can’t teleport.

Claw. Melee Attack Roll: +19, reach 20 ft. Hit: 24 (4d6 + 10) Slashing damage.

Frightful Presence. Each creature of the worm’s choice within 120 feet of it and aware of it must succeed on a DC 19 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 worm 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 worm’s Frightful Presence for the next 24 hours.

Dimensional Beam (Recharge 5–6). The worm exhales a beam of energy in a 120-foot line that is 10 feet wide. Each creature in that area must make a DC 27 Dexterity saving throw, taking 110 (20d10) force damage on a failed save or half as much damage on a successful one. If this damage reduces the target to 0 hit points, it is disintegrated.

Swallow. The worm 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 Grappled ends. While swallowed, the creature has the Blinded and Restrained conditions and can’t teleport, it has Total Cover against attacks and other effects outside the tarrasque, and it takes 56 (16d6) Acid damage at the start of each of the worm’s turns.

If the worm takes 60 damage or more on a single turn from a creature inside it, the worm must succeed on a DC 20 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, each of which falls in a space within 10 feet of the worm and has the Prone condition. If the tarrasque dies, any swallowed creature no longer has the Restrained condition and can escape from the corpse using 30 feet of movement, exiting Prone.

Legendary Action Uses: 3. Immediately after another creature’s turn, the worm can expend a use to take one of the following actions. The worm regains all expended uses at the start of each of its turns.

Attack. The worm makes one claw attack.

Teleport. The worm magically teleports, along with any equipment it is wearing or carrying, up to 120 feet to an unoccupied space it can see.

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