Amphibious. The merrow can breathe air and water.
Multiattack. The merrow makes two attacks, using Bite, Claw, or Harpoon in any combination.
Bite. Melee Attack Roll: +6, reach 5 ft. Hit: 6 (1d4 + 4) Piercing damage, and the target has the Poisoned condition until the end of the merrow's next turn.
Claw. Melee Attack Roll: +6, reach 5 ft. Hit: 9 (2d4 + 4) Slashing damage.
Harpoon. Melee or Ranged Attack Roll: +6, reach 5 ft. or range 20/60 ft. Hit: 11 (2d6 + 4) Piercing damage. If the target is a Large or smaller creature, the merrow pulls the target up to 15 feet straight toward itself.