Keen Smell. The bear has advantage on Wisdom (Perception) checks that rely on smell.

Brave. The bear has advantage on saves against being frightened.

Thick Fur. The bear has resistance to any slashing and bludgeoning damage dealing less than 15 damage. It also has resistance to cold damage, and advantage on saves made to resist the effects of cold weather or spell effects that would deal cold damage.

Give them an inch. The bear’s Bite opportunity attacks have advantage and deal one extra die of damage.

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

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) piercing damage and the target must succeed on a DC 15 STR save or become grappled.

Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.

Apex Predator. When the bear is reduced to less than 10 hit points, but not zero, it may use its reaction to roll a number of d10s equal to its remaining hit dice and gain temporary HP equal to the result. The bear must finish a short rest before it can use this feature again.

The Underdark White Bear has 3 legendary actions that it can spend on any of the below effects. It may do so once only at the end of another creature’s turn.

Claw. (1 action) The bear makes a claw attack against a creature it can see or hear within range.

Roar. (2 actions) The bear roars and all creatures in a 15-foot cube directly in front of the bear must succeed on a DC 15 WIS save or become frightened for 1 minute. A creature can repeat the save at the end of each of its turns, ending the effect on a success. A creature that succeeds is immune to the effect for 1 hour.

Pin down. (1 action) The bear pins a creature it’s grappling underfoot, restraining it and keeping it prone. While restrained in this way, the creature has vulnerability to the bear’s attack damage. A creature can escape this with an Athletics or Acrobatics check contested by the bear’s Athletics.