Biamī's Giant Scorpion

Skin of Steel
Biamī's Giant Scorpion has advantage on saving throws against being poisoned.
Biamī's Giant Scorpion doesn't need to eat, drink, or breathe.
Biamī's Giant Scorpion is immune to disease.
Biamī's Giant Scorpion doesn't need to sleep, and magic can't put it to sleep.

Grappler
Biamī's Giant Scorpion has advantage on attack rolls against a creature it's grappling.
Biamī's Giant Scorpion can use it's action to try to pin a creature grappled by it. To do so, it makes another grapple check. If it succeeds, it and the creature are both restrained until the grapple ends.

Sentinel
Biamī's Giant Scorpion has mastered techniques to take advantage of every drop in any enemy's guard, gaining the following benefits.

When it hits a creature with an opportunity attack, the creature's speed becomes 0 for the rest of the turn.
Creatures provoke opportunity attacks from it even if they take the Disengage action before leaving it's reach.
When a creature makes an attack against a target other than it(and that target doesn't have Sentinel), it can use it's reaction to make a melee weapon attack against the attacking creature.

Multiattack. The scorpion makes three attacks: two with its claws and one with its sting.

Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 6 (1d8 + 4) bludgeoning damage, and the target is grappled (escape DC 12). The scorpion has two claws, each of which can grapple only one target.

Sting. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 4) piercing damage, and the target must make a DC 12 Constitution saving throw, taking 22 (4d10) poison damage on a failed save, or half as much damage on a successful one.