Corrupted Cave Bear

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

Abyssal Corruption. The bear has been infected by water corrupted by the Abyss, and has been overtaken by an unstoppable rage. It gains resistance to bludgeoning, piercing, and slashing damage from nonmagical weapons. Its proficiency bonus is added to its weapon attacks (already included in statblock. If the creature has a bite attack, this attack deals 1d6 additional poison damage, and the target must make a Constitution saving throw (based on 8 + proficiency bonus + constitution modifier). On a failure, the target is poisoned. If the target fails by more than 5, the target is corrupted by the Abyss. See the Abyssal Corruption table in Chapter 2 of the Dungeon Master's Guide for effects the target may suffer.

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

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (1d8 + 7) piercing damage, as well as 3 (1d6 ) poison damage, and the target must make a DC 13 Constitution saving throw. On a failure, the target is poisoned, and on a failure of 5 or more, the target is corrupted by the Abyss.

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