Cave Troll

If the troll has an arm, it loses an arm. It loses one of its claw attacks, and the severed arm can make a claw attack.

If the troll has a head, it loses its head. It loses its bite attack, and the severed head can make a bite attack.

The troll has advantage on Perception checks that rely on smell.

The troll regains 10 hit points at the start of its turn. If the troll takes radiant damage or is exposed to sunlight, this trait doesnt function on its next turn. The troll is petrified if it starts its turn with 0 hit points and doesnt regenerate.

If the troll is dealt a critical hit with a slashing weapon, one of its extremities is severed. The extremity has AC 15, 10 hit points, a Speed of 10, and the trolls Regeneration trait. The troll controls the severed extremity and perceives through it with the appropriate senses (for instance, it sees through the eyes of its severed head). As a bonus action, the troll can reattach the extremity. While the troll is missing the extremity, its maximum hit points are reduced by 10. Roll d6 to determine the severed extremity:

Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage.

Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 9 (2d4 + 4) slashing damage.

The troll attacks with its bite and twice with its claw. When the troll uses Multiattack it can make a rock attack in place of one claw attack.

Ranged Weapon Attack: +7 to hit, range 20/60 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.