Keen Smell. The troll has advantage on Wisdom (Perception) checks that rely on smell. Regeneration. The troll regains 1d10 hit points at the start of its turn. If the troll takes acid or fire damage, this trait doesn't function at the start of the troll's next turn. The troll dies only if it starts its turn with 0 hit points and doesn't regenerate more than the damage below 0 it took last turn.
Multiattack. The Troll makes up to two attacks, one with its Bite or two with its Punch. Bite. Melee Weapon Attack: +6 to hit, reach 5 ft, one creature. Hit: (2d6+4) piercing damage. Punch. Melee Weapon Attack: +6 to hit, reach 5 ft, one creature. Hit: (1d4+4) bludgeoning damage. Fast Regeneration. The troll uses its action regain a further 1d10 hit points. If the troll took acid or fire damage on its last turn, it cannot take this action until the start of the troll's next turn.