Legendary Resistance (3/Day). If Buscemi fails a saving throw, he can choose to succeed instead.

"How do you do, fellow kids?"  Buscemi automatically succeeds on any Charisma Saving Throws, as well as any Charisma (Persuasion) or Charisma (Deception) checks.

Reflective Abdomen. Any time Buscemi is targeted by a magic missile spell, a line spell, or a spell that requires a ranged attack roll, roll a d6. On a 1 to 5, Buscemi is unaffected. On a 6, Buscemi is unaffected, and the effect is reflected back at the caster as though it originated from Buscemi, turning the caster into the target.

Rebuke The Violent. Buscemi deals double damage to enemies that attack him or his allies.

Multiattack. Buscemi can use its Buscemi Presence. It then makes five attacks: one with its Buscemi Beatdown or Buscemi [DESTROY THE INFIDELS] (you choose each time), and four with it's Buscemi Bonk.

Buscemi Beatdown! Melee Weapon Attack: +19 to hit, reach 15ft., one target. Hit: 28 (4d8 + 10) slashing damage, and must roll percentile dice. If the target rolls below 50 percent, they are permanently paralysed. This can be cured by nothing short of a Wish spell.

Buscemi Bonk! Melee Weapon Attack: +19 to hit, reach 10ft., one target. Hit: 32 (4d10 + 10) piercing damage. The target must succeed on a DC 20 Constitution saving throw or be stunned until the end of their next turn.

Buscemi [DESTROY THE INFIDELS] 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 magically teleported to Buscemi's demi-plane for up to 7 days. They can escape early by succeeding on a DC 18 Intelligence (Arcana) Check, Wisdom (Survival) Check, or a successful check with Navigator's Tools as they try to escape the Maze Of Buscemi.

Buscemi's Presence. Each creature of Buscemi's choice within 120 feet of it and aware of it must succeed on a DC 18 Wisdom saving throw or become charmed for 1 minute. A creature can repeat the saving throw with disadvantage, ending the condition on a success.

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

Attack. The tarrasque makes one Buscemi attack.

Move. The tarrasque moves up to its speed.

Infidel Crusher (Costs 2 Actions). Buscemi uses his Buscemi [DESTROY THE INFIDELS] attack.