D&D Monster Monday: Sea Spawn

D&D Monster Monday Sea Spawn

“What’s happening to me!?” you scream as you feel your bones shift and turn. Your skin painfully twists and stretches. The sea hag chuckles as you scream for this unholy transformation to stop. You look down at your newly-webbed hands. You have been marked. Cursed to live your life as a sea spawn.

If you follow me on Twitter you’ll (possibly) know that I’m out sailing the 7 seas this week. That being the case, I felt it was only fitting to pick out an aquatic creature. But I wanted to go with something a bit more obscure than a typical choice such as the merrow.

I came across the sea spawn from Volo’s Guide to Monsters. Admittedly, I didn’t pick these unfortunate creatures due to them being fun to use in terms of their mechanics. It was their lore that drew me in.

That being said, they do have some interesting customization baked-into them. You have to choose at least one unique ability for your sea spawn sort of like the Simic Hybrid in Guildmaster’s Guide to Ravnica.

This is a mechanic that’s becoming increasingly popular and I wanted to show it off in a low CR creature for starters.

So raise the sails, man the bow, (I have no idea how ships work) and be sure not to piss off any krakens or sea hags. Today we dive into the statblock of the sea spawn!

creature from the black lagoon
Ooooo very spooky! Credit: Universal Pictures.

Sea Spawn Lore

Sea spawn are considered to be like boogymen. They are focal points of tall tales and sea shanties warning sailors to respect the sea, to not fall in love with a sea elf, or be wary of a sudden storm out on the seas. Truth be told, the tales are most likely a load of bullshit, but sea spawn are absolutely a real threat to sailors.

By that, I mean the sea spawn themselves aren’t necessarily the threat. Whoever turned these people into sea spawn are the real threat!

These creatures were once humans that were lost at sea or just at the wrong place at the wrong time. Magical sea creatures such as sea hags, storm giants, or krakens took advantage of these people’s unfortunate circumstance and marked them.

This mark transforms a person into a sea spawn. They’ll grow webbed appendages and gills, and they’ll be covered with various sea creature-esque biology like seaweed for hair or barnacles that cover their torso.

Regardless of their appearance, they are now beholden to a master, cursed to never leave the sea again.

This is an interesting parallel to a previous Monster Monday creature, the yuan-ti broodguard. Yuan-ti broodguard typically originate as humans that are magically transformed into snake-like servants to the yuan-ti.

Sea spawn are excellent plot hooks. Why are these creatures marking humans? Is there a pattern? You could start off an entire aquatic campaign by throwing a few sea spawn into the mix!

Sea Spawn Stats and Abilities

You can find the sea spawn’s statblock on page 189 of Volo’s Guide to Monsters.


Size: Medium humanoid
AC: 11 (natural armor)
HP: 32 (5d8 +10)
Speed: 20 ft., swim 30 ft.
STR: 15 (+2)
DEX: 8 (-1)
CON: 15 (+2)
INT: 6 (-2)
WIS: 10 (+0)
CHA: 8 (-1)

“Nothing remarkable” is the way to describe the majority of the sea spawn’s statblock. It’s a fairly average creature. I mean, look at their spread of ability scores! They have two +2’s, two -1’s, a -2, and a +0. Add everything together and the outcome is 0.

That’s a bit hyperbolic, but they’re truly not remarkable at anything, but they’re serviceable for being low CR melee creatures.

Their AC is just god-awful though and thankfully they have a solid chunk of HP to make up for it. Sea spawn can take a punch from a low-level party, but they’re going to be taking a lot of them due to their very low AC.

It’s evident that the sea spawn is at their most effective when they’re in the water. They boast a 30 ft. swim speed which is 10 ft. per turn faster than their regular speed. This also means that they can glide through the water without it counting as difficult terrain.

Their statblock as a whole will work whether in or out of the water, but being amphibious creatures not hindered by underwater combat, they’ll at least have some noticeable advantages over the average adventuring party in the water.

Resistances, Immunities, Saves, and Skills

Senses: darkvision 120 ft., passive Perception 10
Languages: understands Aquan and Common but can’t speak
CR: 1 (200 XP)

At first glance, there’s nothing super interesting going on with the sea spawn’s statblock. They don’t have any damage or condition immunities, saving throw proficiencies, or vulnerabilities. Just some darkvision and languages.

However, one thing to note is that they have drow-level darkvision of 120 ft. Except this doesn’t come with any of the drawbacks of Sunlight Sensitivity. This isn’t an enormous game-changer, but it does give them the advantage of being able to see their target before their target can see them.

They also cannot speak any languages. They can understand Aquan and Common, but that’s it. This has some heavy lore implications.

Creatures like sea hags that can create sea spawn obviously do not want their marks to go off and warn other humans of their fate. By ensuring that sea spawn cannot speak, they’ve ensured that the only information that sailors have about sea spawn are their sea shanties and unreliable tall tales.

Abilities and Traits

Limited Amphibiousness. The sea spawn can breathe air and water, but needs to be submerged in the sea at least once a day for 1 minute to avoid suffocating.

Limited Amphibiousness is one of the odd traits where it doesn’t add anything to the creature’s statblock. In fact, all it does is give them a mechanical drawback.

If anything, this trait is included solely for lore implications. It is how the creatures that create sea spawn ensure that they cannot leave the sea without perishing rather quickly.

They cannot speak, and they cannot leave the ocean for long periods of time. Sea spawn are truly trapped.


MultiattackThe sea spawn makes three attacks: two unarmed strikes and one with its Piscine Anatomy,

Unarmed Strike. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) bludgeoning damage.

A CR 1 creature with a Multiattack of 3 separate attacks is really damn good. The interesting part of this is that Piscine Anatomy is customizable. We’re provided with 3 separate actions in the statblock, but it’s easy enough to homebrew your own options given these examples.

Unarmed Strike is ok in terms of damage output. +4 to hit for 4 average damage is slightly below average, but as a whole, the sea spawn still comes out on top in terms of their average damage per round.

Because of all the options that we have for Piscine Anatomy, I felt that it deserved its own section this article.

Piscine Anatomy

Piscine Anatomy. The sea spawn has one or more of the following attack options, provided it has the appropriate anatomy:

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 4 (1d4 + 2) piercing damage.

Poison Quills. Melee Weapon Attack: +5 to hit, reach 5 ft., one creature. Hit: 3 (1d6) poison damage, and the target must succeed on a DC 12 Constitution saving throw or be poisoned for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Tentacle. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 5 (1d6 +2) bludgeoning damage, and the target is grappled (escape DC 12) if it is a Medium or smaller creature. Until the grapple ends, the sea spawn can’t use this tentacle on another target.

So first of all, you need to be sure that your sea spawn have the apropriate anatomy. They can have the anatomy to do all 3 of these attacks or a combination of 2, but make sure it’s realistic for them to do so. Again, these creatures are all about their story and lore, emphasize that with their statblock.

Bite is a slightly more powerful version of their Unarmed Strike. It deals the same amount of damage but has a +5 to hit. It’s also nice because I’d assume that most sea spawn have this Piscine Anatomy by default.

Poison Quills is a very strong option if you’re looking for some crowd control and survivability. If a creature fails the DC 12 Constituion save they’ll have disadvantage on their attacks for as long as they’re poisoned by Poison Quills. It deals less damage on average than Bite, but it’s better because of the saving throw.

I’d argue that Tentacle is the best option out of the three. For starters, it deals 1 more average damage than Bite and Unarmed Strike, which does add up. It also has a reach of 10 ft. which is cool. But most importantly, it has a grapple that automatically succeeds if the sea spawn hits the target.

The escape DC of 12 isn’t spectacular, but it’s enough to be an annoyance and possibly displace the party’s front-line in a pinch.

Sea Spawn Strengths

Customizable to Fit Whatever Niche is Needed

The sea spawn’s Piscine Anatomy gives the DM some additional tools to work with. This is fun from a mechanical standpoint for the DM, but it also keeps the party on their toes. Each sea spawn they face could be completely different from the previous ones.

They can be modified to become excellent grapplers with a couple of tentacles. A sea spawn could also be focused on imposing the Poisoned condition on their enemies, making it more difficult for them to make successful attacks.

The three options listed in the statblock give the DM a good range of abilities to work with to create their own homebrewed Piscine Anatomy as well. We know a lot from taking a look at these examples.

  • +5 to hit with an attack
  • DC 12 for saving throws
  • The attacks deal between 3-5 damage

Stick within those guidelines and whatever new Piscine Anatomy you create will be perfectly balanced.

Solid Damage and Action Economy

Depending on what Piscine Anatomy the sea spawn uses on their turn, they can deal between 11 and 13 damage between 3 attacks. This is certainly above-average for a CR 1 creature.

The cool thing about sea spawn, though, is that they have a few different options that they can take with their Piscine Anatomy. This is assuming that the sea spawn can physically do any of the three options.

You can opt to deal slightly more-consistent damage with Bite, you can deal damage and impose the Poisoned condition with Poison Quills, or you can deal a lot of damage and grapple a target with Tentacle. Sea spawn can adapt to the encounter as needed without sacrificing their action economy to do so.

Sea Spawn Weaknesses

Abhorrent Defenses

Every attack that the sea spawn has in their arsenal, except Tentacle, has a range of 5 ft. This means that they’re going to need to be on the front-lines to take full advantage of their attacks.

This isn’t a problem in it of itself. However, when this is coupled with a creature that has an AC of 11 and sub-par Dexterity and Wisdom modifiers it’s a problem. Sea spawn are easily hit and can easily be crowd controlled by spells.

They have an above-average Constitution modifier which is beneficial to those saving throws. Sea spawn also have a solid chunk of HP thanks to their +2 Constitution modifier. Regardless, it’s not enough to totally offset the rest of their shortcomings in terms of defenses.

Sea spawn do their best work in melee range. The issue is that melee combat imposes more opportunities for the enemy to deal damage. With 11 AC, the sea spawn are going to be hit constantly.

No Ranged Attack Options

By rules as written (RAW), sea spawn have no ranged attack option. If they have a tentacle that can realistically use the Tentacle Piscine Anatomy then they have a single attack at a 10 ft. reach. This isn’t much considering they have to close the gap to use their two Unarmed Strikes.

Due to their lack of defenses, they’re practically sitting ducks if they cannot bridge the gap between themselves and their target. It would have helped them considerably to have at least some ranged attack by RAW for those instances where they cannot get into melee range of their target.

You can certainly homebrew your own Piscine Anatomy that provides your sea spawn with a single ranged attack per turn. It wouldn’t be difficult to give them the equivalent of a shortbow or a poisoned dart or something. Doing so would certainly shore up one of their statblock’s weaknesses.

How to Play a Sea Spawn

Just Keep Swimming

Given their lore, sea spawn won’t venture far from the sea anyway. Regardless, be sure to plan their encounters around water as that’s where their statblock’s strengths lie.

Murky water full of plant life can give them the edge to fully-utilize their 120 ft. of darkvision. They can see the party coming before the party can see them, plus since they’re able to breathe underwater they can simply wait until the party puts themselves out of position.

Sea spawn are going to see their best results in underwater combat, where they have a natural swim speed and attacks that don’t receive penalties in underwater combat. Depending on the party’s classes and composition they may have some huge disadvantages for fighting underwater.

Rush Into Melee and Stick There

For the best combat results, your sea spawn are going to have to rush into melee range of their enemies and stay there. This is challenging if they are on land since they have very below-average movement speed.

A PC can just disengage and get between 5-10 ft. away from the sea spawn depending on their race. If you let the PCs make a gap, even for one turn, your sea spawn become much less threatening.

My recommendation to counter this is that if you have a sea spawn encounter on land, they need to all have at least one tentacle. If a creature is grappled they will not be able to abuse the sea spawns’ poor movement speed and kite them around the battlefield.

This conundrum isn’t even an issue though if you can engage the party underwater with your sea spawn. In fact, it shifts the balance in the opposite direction.

Now the party is most-likely slower than the sea spawn and they have to figure out ways to create distance between themselves and the sea spawn.

Utilize your environment and your grapples to keep your enemies within range of your melee attacks, otherwise, you’re just chum in the water.


The sea spawn’s statblock isn’t anything to write home about. They have abysmal defenses, mediocre stats, and a movement speed that is dependent on the environment the encounter takes place.

However, they have some fantastic lore and their Piscine Anatomy makes them interesting characters to rekit and fiddle around with as a DM. You could create many different plot hooks for you adventurers to dive into with their existence in your campaign alone.

All in all, I like them a lot from a story perspective, but they have some glaring weaknesses for your party to exploit. You shouldn’t bank on them as being a difficult or engaging encounter on their own, but they make for fun trash mobs with a bit of creativity!

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  1. spiderwrangler says:

    Movement isn’t combined, they will have a max move (without dashing) of 30 ft, either by swimming 30, or walking 20 and swimming 10. After one move is used up, the distance moved is subtracted from any other move speeds.

    1. James Griffith says:

      Good catch, thank you! I’ll update this later today.

      I thought I updated all these when I was corrected previously but I must have missed this one!