Few things are as iconic in a fantasy setting as the lure of the Siren’s Song, the enticing melody that has charmed countless listeners to thier dooms. This trope goes as far back as the Odyssey where the hero Odysseus must navigate the Argonaut past a choir of aquatic temptresses, by stuffing wool in his ears to deafen the song, Odysseus pilots his crew to safety.
But in Dungeons and Dragons 5e, only two monsters come prepackaged with the ability to charm their target using song: the Harpy and its higher CR upgrade the Harpy Matron. This Monster Monday we take a stab at adding the Luring Song feature to two more monster stat blocks, creating variations of frightful creatures to bewitch and beguile your party.
The Sewer Sirens
The Rhyth-Mimic
Conclusion
Chill you to the Merrow
We start with the merrow; a depraved underwater monstrosity that craves the taste of humanoid flesh. According to the lore in the Monster Manual, the merrow were once normal merfolk that had the unlucky fortune of discovering an idol dedicated to Demogorgan. Like everything associated with the demon lord of chaos, the merfolk were horrifically transformed by madness that permeated the effigy.
Now their own distinct race, and vehemently evil, these twisted variants of merfolk use their teeth-filled jaws to tear flesh from their prey. The merrow have almost everything ready to go right out of the book for our first siren adaptation.
Duplicating the harpy’s luring song feature is an easy modification to the malevolent merfolk, but the thalassic siren known to lure sailors to their demise has been done countless times before. So how can we keep this monster interesting, and more than just an easy ocean encounter that your party demolishes in a few rounds? By moving it to a new locale: the sewer system beneath a large city.
Combat
This merrow hunts prey from the labyrinthine underground of a thriving metropolis, rarely leaving the safety of its tunnels. Instead the monster uses the Luring Song feature to charm victims into its subterranean lair where it devours them leaving nothing behind but bones and discarded mementoes.
In combat this merrow uses flooded portions of the infrastructure to gain advantage over invading adventurers, using stealth to swim underwater into melee range of the combatants. The harpoon can be re-flavored as a discarded spear that the party recognizes as the weaponry of the city guard. Or it could be handcrafted from the bones of past victims. Use your imagination here to add your own flavor or change the weapon to something new all together. Maybe in your campaign the merrow prefers to attack up close and personal with only its teeth and claws.
Setting the Hook
Disappearing citizens help create the perfect plot hook to get your players motivated. Why did the party’s favorite city guard go missing? Does the city politician need to find the culprit behind his disappearing constituents before his big election or risk losing the race? One of the party members could even be lured in by the merrow’s spell, breaking free before they can become the monster’s next meal.
That uneasy, hagging feeling…an alternative to the Merrow
Taking inspiration from the child eating monster from the famous Stephen King book, a sea hag would be an easy upgrade for the luring song merrow. The sea hag stat block comes with an ability to create an illusionary form that the hag uses to disguise itself, just like the monster from the novel. But the hags illusions come with a few caveats important to remember.
The illusion is a reflection of the sea hag’s hideous nature. The sea hag is a repulsive fae creature and its magic is proof of that. You can use this flavor to add more narrative to your game. When describing the illusion, if you use something familiar to the players; say an evil child eating clown, lean into how the monster’s appearance seems off, distinguishing marks seem exaggerated and overstated. Ugly doesn’t have to mean unsightly, it can just as easily mean unnatural.
The illusion won’t hold up to physical inspection. When a creature comes into contact with the spell anything that touches the illusion will pass through revealing the facade underneath.
With the sea hag’s illusion ability you have a visual element to help add an extra sense into your story adapting the monster to take on different appearances to suit your needs. This may also allow you to introduce the monster as a friendly NPC earlier to your party. The standoffish barmaid with pockmarked skin. A gruff and ugly city guard that stands watch outside the orphanage. That NPC could have secretly been the man-eating monster.
The Rhyth-Mimic
The mimic is the quintessential shape changing monster in Dungeons and Dragons. Able to shift its form to whatever object is best suited to blend into the environment, the mimic is a persistent predator that waits for prey to come to it. But even mimics can become impatient in the fast paced dungeon world of Dungeons and Dragons. This variant of the mimic takes advantage of the Luring Song feature to compel creatures to either touch it or coerce a target into range of its pseudopod attack.
Sight, Sound and…Touch?
What form would this mimic take? A music box is the first thing that comes to my mind. A musical instrument like a harp or organ would make a fitting camouflage for a mimic in a “Phantom of the Opera” style campaign. Or maybe in your game, after devouring a touring band of bards, a nest of mimics have stolen the shape of an entire assemble of instruments and impersonates the bands greatest hits.
Your mimic doesn’t have to take the form of a musical object. This mimic could disguise itself as a mirror that reflects the image of a forlorn lover, the reflection sings a melancholy tune lamenting a lost love. This song, the mimic heard decades ago from a previous meal, could be part of an urban legend about a cursed mirror haunted by a ghost. As an adventure hook an innkeeper or local gossipmonger in your campaign may talk of the haunted mirror and the many adventurers that go missing after searching for it.
In a modern campaign setting your Rhyth-Mimic might take the form of a kitchen sink with a mouth disguised as a garbage disposal/drain combo. The mimic entices the target of its song with the empty promise of a long forgotten token, and if only they would reach into the drain opening they would find the lost keepsake.
In a more traditional setting your adventure could be littered with juvenile mimics like the ones introduced in Tasha’s Cauldron of Everything. These infants could take the form of conch shells that create ocean sounds like real seashells, their little mouths forming in the opening of the shell facade. Once a player is seduced to pick up the incognito mimic the tiny monstrosity latches onto the player character’s ear and won’t let go. I don’t know about you but this would be absolutely horrifying to me.
Mimic in Action
The Rhyth-mimic abides by the same hunting strategy as a regular mimic; waiting in plain sight for an unsuspecting target. The Rhyth-mimic may target a single creature with its Luring Song ability, or spread a wide net trying to catch more than one victim. When incorporating the new mimic in your game, focus on the ability that makes it unique from the version in the Monster Manual. Describe what the player characters hear when faced with the mimic. Incorporate lore or backstory into the encounter to make it feel grounded with your players.
Curtain Fall
Hopefully this minor tweak to two of Dungeons and Dragons essential monsters sparked a bit of imagination for your next campaign and will help keep your players on their feet. Which monster makes a better Sewer Siren, the sea hag or the merrow? What shape would a Rhyth-mimic take in your game? What would the song of these monsters sound like? Comment below if you're up for sharing.