Chained Troll

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 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.

Body Shield. Goblin handlers can use their reaction to have the troll take damage instead of them when attacked.

Chained. The chained troll cannot move farther than 15 feet from each of its handlers as long as the combined strength of the handlers surpases that of the troll. 

Multiattack. The troll 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: 7 (1d6 + 4) piercing damage.

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

1 Per round of combat. The Troll grabs one of its handlers by pulling from its chain. The target and the goblin both take damage.

Throw Goblin. Ranged Weapon Attack: +4 to hit, reach 15/30 ft., one target. Hit: 7 (1d6 + 4) bludgeoning damage.