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Merrow Mage


AC 13 (natural armor)

HP 45 (6d10 + 12; bloodied 22)

Speed 10 ft., swim 40 ft.

Proficiency +2; Maneuver DC 14

Senses darkvision 60 ft., passive Perception 11

Languages Abyssal, Aquan, Giant, Primordial

Amphibious. The merrow can breathe air and water.

Regeneration. The merrow regains 10 hit points at the beginning of each of its turns as long as it has at least 1 hit point.

Innate Spellcasting. The mage’s innate spellcasting ability is Charisma (spell save DC 12). It can innately cast the following spells, requiring no material components:

At will: darkness , invisibility

1/day: charm person


Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage, and the target is grappled (escape DC 14). Until this grapple ends, the merrow can’t attack a different creature with its claws.

Harpoon. Melee or Ranged Weapon Attack: +6 to hit, reach 10 ft. or range 20/60 ft., one target. Hit: 11 (2d6 + 4) piercing damage. The target makes a DC 14 Strength saving throw . On a failure, the merrow pulls the target up to 20 feet toward the merrow.


Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 6 (1d4 + 4) piercing damage, or 9 (2d4 + 4) piercing damage if the target is grappled .

Mage Bolt (3/Day). The mage targets a creature within 30 feet. The target makes a DC 12 Dexterity saving throw , taking 21 (6d6) lightning damage on a failed save or half damage on a success.

Shapeshift. The mage changes its form to that of a Medium merfolk or back into its true form. While shapeshifted, it can’t use its Bite attack but its statistics are otherwise unchanged except for its size. It reverts to its true form if it dies. 

Darkness (2nd-Level; V, S, Concentration). Magical darkness spreads from a point within 60 feet of the mage, filling a 15-foot-radius sphere and spreading around corners. It remains for 1 minute. A creature with darkvision can’t see through this darkness, and nonmagical light can’t illuminate it.

Invisibility (2nd-Level; V, S, Concentration). The mage is invisible for 1 hour or until it attacks, uses Mage Bolt, or casts a spell.


The merrow grabs creatures in its claws and then bites them. If an enemy is up to 20 feet away, it uses its harpoon and pulls the enemy into its reach. It uses its claws for opportunity attacks so that it can grapple fleeing creatures.


Gimra, Grayblood, Moroch, Sharktooth

Legends and Lore

With a History or Nature check, characters can learn the following:

DC 10 Merrows resemble merfolk , but they are much larger and eat the flesh of both aquatic and land-based humanoids.

DC 15 Merrows snatch prey with harpoons, then tear them to pieces with their claws and shark-like teeth. They seem unusually interested in land-dwellers and may interrogate them before dispatching them.

DC 20 Though they once ruled a mighty undersea empire, merrows now serve creatures such as aboleths , krakens , and sea hags .


Long ago, some merrows allied themselves with the underwater kingdoms of the storm giants , while others learned ancient arcane secrets guarded by ogre mages . Merrow mages now use these powers in concert with sea hags , giant lanternfish (see lamia), and other evil creatures in order to prey on peaceful merfolk .


1 In its lair, feasting on victims

2 Carrying a giant drill which can be used to sink ships

3 Reeling in a harpooned dolphin or giant sea horse

4 Patrolling; attacks on sight


Sharks fighting over a corpse

2 A dead merfolk or sailor tied to a kelp rope

3 Shoals riddled with underwater caves

4 Terrified merfolk


Merrow inhabit drowned caves and dark ocean floors.

CR 0–2 merrow

Treasure 60 gp, 150 sp, elemental gem (water)

CR 3–4 2 merrow ; merrow with giant octopus or hunter shark ; merrow mage

Treasure coral bracelet (125 gp), shark tooth and lapis lazuli necklace (125 gp), potion of healing , potion of water breathing , javelin of lightning

CR 5–10 merrow mage with sea hag ; merrow mage with 1 to 3 merrows ; merrow mage with giant lanternfish (see lamia)

Treasure 600 gp, 1,500 sp, gold compass (125 gp), sealed map case containing nautical charts and a spell scroll of gust of wind , 2 feather tokens (anchor)

Monster Type Description

Monstrosities are magical beings usually native to the Material Plane. Some monstrosities combine the features of beasts and humanoids, like centaurs . Others have bizarre or unnatural appearances, like many-tentacled ropers . Monstrosities could only arise in a world suffused with magic.