Soul Troll

When the Soul Troll takes damage that would reduce it to 0 hit points but not outright kill it, it can drop to 1 hit point instead, unless the damage was acid or fire damage. Once it has used this feature it must finish a long rest before it can do so again.

Melee Weapon Attack: your proficiency bonus + its Strength modifier to hit, reach 5 ft., one target. Hit: 1d8 + its Strength modifier bludgeoning, piercing or slashing damage.