Bear of Skoraeus

Keen Smell. The Bear of Skoraeus has advantage on Wisdom (Perception) checks that rely on smell.

Legendary Resistance (3/Day). If the bear fails a saving throw, it can choose to succeed instead.

Rebirth. If the bear is slain, it's body is transformed into energy and absorbed by the enormous gemstone hanging from its neck. The bear returns to life at sunrise after 1d4 days have passed. The gemstone is immune to physical damage and can only be destroyed by a disintegrate spell or similar magic.

Multiattack. The bear makes three attacks: one with its bite and one with each of its claws.

Earth Stun (Recharge 5-6). The Bear of Skoreaus slams both of its paws into the ground, sending a shock wave that affects any creature within 120 feet of it. Each affected creature must succeed on a DC 21 Constitution Saving. On a failed save, the creature takes 4d10 bludgeoning damage and their feet and legs become fused to the ground and begin turning to stone, causing them to be restrained. On a successful save, a creature takes half damage and suffers no additional effects. Creatures repeat the saving throw at the end of each of their turn, ending the effect on a success. If a creature fails the saving throw three consecutive times, they become petrified.

Ignite Hide (Recharge after a Short or Long rest). The Bear of Skoreaus uses its right paw to ignite its own fur and hide on fire. It remains ablaze for one minute or until it uses an action to extinguish the flames. While ablaze, the Bear of Skoreaus takes 7 (2d6) fire damage at the start of each of its turns, and enemies within 10 feet of it take 14 (4d6) fire damage at the start of each of their turns. Additionally, while ablaze, the bonus cold damage dealt by the left claw attack is instead fire damage like the right claw.

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 22 (3d8 + 9) piercing damage plus 11 (3d6) lighting damage.

Right Claw. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit:  20 (3d6+9) piercing damage plus 11 (3d6) fire damage.

Left Claw. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit:  20 (3d6+9) piercing damage plus 11 (3d6) cold damage.

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

Claw attack. The bear uses one of its claw attacks.
Ignite/extinguish (costs 2 actions). The bear uses its Ignite Hide ability if it is available to it
Diamond hide (costs 3 actions). The bear's skin becomes solid diamond and it gains immunity to all damage from the next creature that would deal damage to it until the end of that creature's turn. This effect ends at the start of the bear's turn.