Clumsy Flyer. The Cockroach That Ate Cincinnati cannot sustain flight for more than one turn.

Legendary Resistance (1/Day). If the Cockroach That Ate Cincinnati fails a saving throw, it can choose to succeed instead.

Siege Monster. The Cockroach That Ate Cincinnati deals double damage to objects and structures.

Survivor. If damage from an attack reduces the Cockroach That Ate Cincinnati's hit points to zero, it takes a Constitution saving throw with DC of 5 plus the damage taken. On success, the hit points drop to 1 instead.

Multiattack.  The Cockroach That Ate Cincinnati use its Frightful Presence. It then makes five attacks: two with its bite and three with its stomp. 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 Cockroach That Ate Cincinnati can't bite another target.

Stomp. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit:  36 (4d12 + 10) bludgeoning damage. If the target is a creature, it becomes incapacitated (dodge DC 20). Until the Cockroach That Ate Cincinnati lifts its leg, the target takes damage every turn (escape DC 25).

Frightful Presence. Each creature of the Cockroach That Ate Cincinnati's choice within 120 feet of it and aware of it must succeed on a DC 17 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 Cockroach That Ate Cincinnati 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 tarrasque’s Frightful Presence for the next 24 hours.

Swallow. The Cockroach That Ate Cincinnati 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, 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 tarrasque’s turns.

If the Cockroach That Ate Cincinnati takes 60 damage or more on a single turn from a creature inside it, the Cockroach That Ate Cincinnati 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 Cockroach That Ate Cincinnati. If the Cockroach That Ate Cincinnati 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 Cockroach That Ate Cincinnati 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 Cockroach That Ate Cincinnati regains spent legendary actions at the start of its turn.

Attack. The Cockroach That Ate Cincinnati makes one bite attack.

Move. The Cockroach That Ate Cincinnati moves up to half its speed.

Chomp (Costs 2 Actions). The Cockroach That Ate Cincinnati makes one bite attack or uses its Swallow.