Multiattack

The lake troll makes one Bite attack and two Claw attacks. If both Claw attacks hit one creature that is wielding a weapon, the target must succeed on a DC 16 Dexterity saving throw or the target's weapon takes a permanent and cumulative −1 penalty to damage rolls. If the weapon's penalty drops to −5, the weapon is destroyed. If the target is wielding more than one weapon, the troll chooses which weapon to affect.

Bite

Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 6) slashing damage.

Claw

Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 15 (2d8 + 6) piercing damage.