Half-Tarrasques are resistant to high temperatures and fire. Half-Tarrasques are weak to acidic items.

Blindsight 25 ft

On a succeeded intimidation check, you apply the frightened effect to the target.

Strength +2 Constitution +2 Charisma -2 Intelligence -2

Tarrasque born reach adulthood in their late early twenties and for longer than a Millennia.

at level 20, you get an extra action

You can transform into a mini tarrasque (which is your current size) You can do 1 of 3 attacks:

Bite: You can bite someone and they must make a dc 12 acrobatics to save or their Body is stuck to your teeth making them become grappled and they take 1d8 damage + your str mod (the dice count goes up every 8 levels) and they can make another dc 10 save to get out of your bite or take 1d4 piercing per round. On a crit fail you can bite a chunk out of the enemy and if the enemy rolls another critical fail (in a row) you can eat the enemy (if they are a lower size class) and they will take 2d12 + Constitution modifier acid damage per round. When you eat the enemy they have a disadvantage on their attack rolls. On a dc 12 strength check the enemy is spat out like a bad meal.

Claw: You can claw at someone dealing 1d4 + (your strength mod) slashing damage and 1d4 piercing damage (the dice count does up every 10 levels).

Tail attack: You can attack someone with your tail and they must make a dc 10 acrobatics save. on a fail, the enemy can take 1d4+ 1 bludgeoning damage and knock prone.

Every 10 levels your size goes up 1 category. (If your dm would allow this)

Your current natural Ac is your transformed Ac