Aquatic Troll

Aquatic.  This creature is able to  breathe both air and water

generation. The aquatic troll regains 10 hit points at the start of its turn if it is in contact with or submerged by a source of water. If the aquatic troll takes lightening or thunder damage,  or if the aquatic troll is not in contact with water, this trait doesn't function at the start of the troll's next turn. The aquatic troll dies only if it starts its turn with 0 hit points and doesn't regenerate.

Multiattack. The troll makes three attacks: one with its seaweed trap and two with its claws.

Seaweed Trap. Ranged Weapon Attack: +7 to hit, range 10/30 ft., two targets within 5ft of each other. Hit: A Large or smaller creature hit by a seaweed trap is restrained until it escapes. The seaweed trap has no effect on creatures that are formless, or creatures that are Huge or larger. A creature can use its action to make a DC 10 Strength check, freeing itself or another creature within its reach on a success. Dealing 5 slashing damage to the trap (AC 10) also frees the creature without harming it, ending the effect and destroying the net.

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