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

Regeneration. The troll regains 10 hit points at the start of its turns. If the troll takes acid or fire damage, this trait doesn't function at the start of its next turn.

Multiattack. The troll can make three attacks: one with its bite and two with its claws. 

Bite. Melee Weapon Attack: +7 to hit, reach 5ft., one target. Hit: 6 (1d6 + 4) piercing damage plus 4 (1d8) cold damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit:  6 (1d8 + 4) slashing damage plus 5 (1d8) cold damage. If the target takes any of the cold damage, the target must succeed on a DC 15 Constitution saving throw or have disadvantage on its attack rolls until the end of its next turn.