Tarrasque

If the monster fails a saving throw, it can choose to succeed instead.

The monster has Advantage on saving throws against spells and other magical effects.

If the monster is targeted by a Magic Missile spell or a spell that requires a ranged attack roll, roll .
On a 1-5, the monster is unaffected.
On a 6, the monster is unaffected and reflects the spell, turning the caster into the target.

The monster deals double damage to objects and structures.

The monster makes one attack and three other attacks, using or in any combination.

. , and the target has the Grappled condition (escape DC ). Until the grapple ends, the target has the Restrained condition and can't teleport.

. .

. . If the target is a Huge or smaller creature, it has the Prone condition.

Constitution Saving Throw: DC , in a -. .
Failure: damage, and the target has the Deafened and Frightened conditions until the end of its next turn.
Success: Half damage only.

Strength Saving Throw: DC , by the monster (it can have up to six creatures swallowed at a time).
Failure: The target is swallowed, and the Grappled condition ends. A swallowed creature has the Blinded and Restrained conditions and can't teleport, it has Total against attacks and other effects outside the monster, and takes damage at the start of each of the monster's turns.
If the monster takes 60 damage or more on a single turn from a creature inside it, the monster must succeed on a at the end of that turn or regurgitate all swallowed creatures, each of which falls in a space within feet of the monster and has the Prone condition. If the monster dies, any swallowed creature no longer has the Restrained condition and can escape from the corpse by using 20 feet of movement, exiting Prone.