Regeneration. Regains 10 hp at start of its turn. If troll takes acid or fire this doesn't function at start of troll's next turn. Dies only if it starts turn with 0 hp and doesn't regenerate.

Uncontrolled Growth. When it regains hp from its Regeneration gains random teratoma. Teratoma and effects last until removed or replaced by another. Troll can have only 3 at a time. If it would gain a 4th oldest fades and is replaced. Teratomas (d6):1 New Senses: A bevy of new ears and noses give troll advantage on Wis (Perception) checks that rely on hearing or smell.2 Many Feet: The troll can't be knocked prone.3 Adrenal Overdrive: Can't be frightened or suffer exhaustion.4 Clinging Limbs: When this teratoma is removed with Fling Limb action it attaches to target. While attached to target target takes 3 (1d6) poison at start of each of its turns. A creature including target can use its action to detach teratoma.5 Echo Chambers: Has blindsight out to a range of 60'.6 New Pain Nerves: Disadvantage on any non-attack roll.