Behir (and other Dragon Slaying Monster) Variants for Dungeons & Dragons 5th Edition

Behirs have been around since first edition, initially appearing in the Lost Caverns of Tsojcanath module. What variants do these weird snake-ipedes have in store for our players? Let’s take a look!

Here’s what to expect from this article:

  • What is a behir?
  • How do behirs fight?
  • Are behirs really dragon slayers?
  • What behir (and other dragon slaying monster) variants are needed?
  • 5 new dragon slaying monster variants.

What is a behir?

The behir didn’t just come from D&D. Like many beasties from first edition, the behir found its roots in folkore, Scottish specifically. Its original name is beithir.

Here’s what Wikipedia has to say about beithirs:

The beithir is a large snakelike creature or dragon in Scottish folklore, possibly originating from sightings of large grass snakes (Natrix natrix) or European eels (Anguilla anguilla).

Basically, the beithir is the Loch Ness Monster.

Dungeons & Dragons behirs are blue serpentine monsters with twelve short legs. They attack their enemies and prey by wrapping them up with their long, scaly bodies so they can crush the life out of them and swallow them whole.

And if that isn’t enough, they can breathe lightning, too.

According to fifth edition lore, behirs were created by giants as a hunter of dragons during the endless Giant/Dragon wars of long ago. In fact, behirs hate dragons so much, that if they so much as even sense a dragon lives near it, it’ll hunt it down and try to kill it.

How do behirs fight?

Keith Ammann sheds some light on the behir’s fighting tactics. You can read about them at his blog The Monsters Know What They’re Doing.

The basic gist is that behirs are cavern predators. They lair in places other beasts can’t reach, and use the dark and their darkvision to their advantage. When prey draws near, they constrict then bite and swallow. Keith hypothesizes that their lightning breath is only used for self-defense.

That’s pretty cool for a basic beastie. But these buggers are supposed to be dragon slayers! So let’s investigate that idea for a second.

Are behirs really dragon slayers?

Based on the behirs stats, it’s a little hard to believe that they’re dragon slayers. At least not anymore.

Imagine that a behir and a dragon get into a fight.

To make matters easy, we’ll just say that the behir is fighting a young red dragon. Both are roughly the same CR, with the behir at 11 and the young red dragon at 10.

Already, the young red dragon has some noticeable advantages. Its armor class is higher, it has marginally higher hit points, and it can fly 80 ft. per turn. The behir and young red dragon have the same Strength, but the behir is much faster than the dragon, Dex and land-speed-wise. Still, the dragon has a much higher Constitution.

But where the dragon really wins is its superior Intelligence. Sure, the behir has better self-preservation instincts with its higher Wisdom, so it knows when to run. But if the dragon’s already out-thunk the beast, chances are the behir won’t even be able to escape.

The young red dragon will stay in the air where the walk/climb behir won’t be able to reach it, only swooping in close enough to drop its fire attack. It will be sure to stay more than 20 ft away, too, where the behir won’t be able to hit the dragon with its own breath attack. And the behir is probably not smart enough to hold its action for when the dragon flies near.

The dragon has a 65% chance of hitting the behir with its full fire breath causing 56 damage on average. This ability recharges every 3 rounds or so, so there’s not much to keep it from staying in the air, waiting for the recharge recharge, and coming back at the behir with its fire once or twice again. When the behir looks pretty wounded, the dragon will sweep in and finish it off with its multiattack.

Let’s say that the behir gets lucky and gets the dragon with its constrict attack. It’s got a pretty good chance of grabbing the dragon, too. That’s 34 damage right there. Then, it will immediately bite the dragon and deal another 22 damage. Pretty painful for the young red dragon!

The dragon has until the next turn to escape. That takes a strength check of 16 which the dragon has a 50% chance of succeeding. It’s already used its action, so its only move is to fly off. However, if the dragon flees, the behir can make an attack of opportunity against the dragon with its constrict and the dragon will wind up right back where it was.

Long story short: dragons should never do close combat with behirs. And they’re smart enough to know that.

Keep in mind, this is just the young red dragon. Adult dragons and ancient dragons could easily avoid getting killed by behirs.

So what were the behirs’ original purpose?

I’ve come to two conclusion as to what the behirs were originally supposed to do in the way of battling dragons.

Conclusion one: behirs used to be a lot bigger, tougher, and smarter than they are now. Once the dragons were mostly depleted, they had to adapt to a world with fewer natural enemies. More than likely, the biggest of the behirs were killed off quick, seeing as they were just as dangerous as the dragons. Those that did survive were those that were better at hiding and capable of finding other food sources. Years went by and they shrank down from their Gargantuan size of yore to their modern Huge size. Additionally, they lost a lot of their mental edge, trading strategic smarts for survival instincts.

Conclusion two: behirs weren’t designed to fight the big guys; they were baby eaters. The behir’s swallow attack works only against Medium or smaller targets. Any dragon over the age of five years is going to be Large or bigger. However, the wyrmlings and eggs are perfect sized for the behir’s dislocated jaw. Behirs were trained to go into dragon lairs, slink through the stones, and eat the babies and unhatched eggs. This kept the dragon population in check. And if mom or dad caught them doing this, the behir used its lightning breath to scare them off and flee with its awesome speed and climbing ability. Being a neutral evil monstrosity, it’s not too hard to imagine this being the case.

What 5e behir variants are needed?

Conclusion two is probably the most realistic of the pair. Yet conclusion one is much more fun. It’s neat to think of an ancient behir–or a beithir, if you will–that was a Gargantuan beast that could breathe some serious lightning and actually posed a major threat for dragons. So that’s one variant.

Instead of crafting a bunch of variants of behirs, instead I got to thinking about the problem the other mythical races were having with dragons in the past. Naturally, they would have all needed their own way to fight them off. And each method would be unique to their race.

The storm giants were clever; they knew to attack the dragons when they’re weakest: at birth and before. Hence, the infanticidal behir.

According to realms lore, the elves were also influential in ridding Toril of the dragon problem. Dwarves had a huge hand in it, as well, using their technology to fight against the dragons.

Classically speaking, there’s always some knight or another questing to kill a dragon. You hear the stories of all the brave heroes that get the job done. But what of those that fail on those quests? What if they rose from the dead to form a mob of dragon slaying ghosts that would restlessly hunt down dragons like a swarm of chivalrous wraiths (this one was Jack’s idea)?

Finally, Tiamat, Goddess of Dragons, is a lady of the Nine Hells. And when you’re in Hell, you do what other devils do: fight demons! Of course, the demons need a way to fight back, so they too would create their own dragon-fighting fiend.

5 new dragon-slaying monster variants for 5e D&D

First up is the gargantuan version of the behir, its ancestor the ancient beithir. They’re bigger, meaner, smarter, and fully capable of going toe-to-toe with an ancient dragon. They’d be pretty rare, having survived for centuries without notice, but they’re just as devilish and clever as their natural enemies.

Next, we have an elven metshataya. Powerful wizards in their own right, the metshataya (which is elvish for “hunter”) have been raised their whole lives to seek out dragons and destroy them. These elves wield powerful glaives which allow them to add their Dexterity modifier to the attack.

Centuries ago, a plucky gnome engineer named Wally Picklepluck developed five powerful automatons each strong enough to battle a young dragon on its own. But when truly pressed, the five could combine to form Foesmasher, a Gargantuan construct capable of toppling even the eldest drakes.

When the restless souls of defeated dragon slayers rise from their graves and come together with the common goal of defeating the beasts that ended their lives, they become a dragon slayer wraith swarm. These ghostly  combatants restlessly stalk the countryside looking for dragons and dragon kin. Driven by an interminable compulsion, they will not let anything stop them until all dragons and dragonkin are removed from Toril.

Finally, the Demon Lords of the Abyss crafted the rullbluts, loathsome tentacle-clad creatures developed to hunt and suck the life from dragons.

As usual, these dragon slayer variants are free for you to use in your 5e Dungeons & Dragons campaigns. Just not commercially! And the art isn’t mine. Borrowed!


Ancient Beithir

Gargantuan monstrosity, neutral evil

Armor Class 19 (natural armor)

Hit Points 312 (16d20 + 128)

Speed 50 ft., climb 40 ft.

Abilities Str 26 (+8), Dex 16 (+3), Con 26 (+8), Int 10 (+0), Wis 16 (+3), Cha 15 (+2)

Saving Throws Dex +9, Con +14

Skills Perception +9, Stealth +9

Damage Immunities lightning

Condition Immunities frightened

Senses darkvision 90 ft., passive Perception 16

Languages Draconic, Giant,

Challenge 18 (20,000)

Legendary Resistance (3/Day). If the beithir fails a saving throw, it can choose to succeed instead.


Multiattack. The beithir makes two attacks: one with its bite and one to constrict.

Bite. Melee Weapon Attack: +14 to hit, reach 15 ft. one target. Hit: 30 (4d10 + 8) piercing damage.

Constrict. Melee Weapon Attack: +14 to hit, reach 5 ft., one Huge or smaller creature. Hit: 24 (3d10 + 8) bludgeoning damage plus 24 (2d10 + 8) slashing damage. The target is grappled (escape DC 18) if the beithir isn’t already constricting a creature, and the target is restrained until this grapple ends.

Lightning Breath (Recharge 5-6). The beithir exhales a line of lightning that is 40 feet long and 10 feet wide.  Each creature in that line must make a DC 18 Dexterity saving throw taking 88 (16d10) damage on a failed save, or half as much damage on a successful one.

Swallow. The beithir makes one bite attack against a Large or smaller target it is grappling. If the attack hits, the target is also swallowed, and the grapple ends. While swallowed, the target is blinded and restrained, it has total cover against attacks and other effects outside the beithir, and it takes 28 (8d6) acid damage at the start of each of the beithir’s turns. A beithir can have only one creature swallowed at a time.

If the beithir takes 50 damage or more on a single turn from the swallowed creature, the beithir must succeed on a DC 18 Constitution saving throw at the end of that turn or regurgitate the creature, which falls prone in a space within 10 feet of the beithir. If the beithir dies, a swallowed creature is no longer restrained by it and can escape from the corpse by using 15 feet of movement, exiting prone.

Legendary Actions

The beithir can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The beithir regains spent legendary actions at the start of its turn.

Detect. The beithir makes a Wisdom (Perception) check.

Move. The beithir moves up to half its speed.

Chomp (Costs 2 Actions). The beithir makes one bite attack or uses its swallow.


Dragon Slayer Wraith Swarm

Huge swarm of medium undead, lawful evil

Armor Class 16 (chain shirts, shields)

Hit Points 283 (27d12 + 108)

Speed 30 ft.

Abilities Str 20 (+5), Dex 16 (+3), Con 19 (+4), Int 6 (-2), Wis 9 (-1), Cha 10 (+0)

Damage Resistances necrotic; bludgeoning, piercing, and slashing from nonmagical attacks

Damage Immunities poison

Condition Immunities charmed, exhaustion, frightened, grappled, paralyzed, petrified, poisoned, prone, restrained, stunned, unconscious

Senses darkvision 90 ft., passive Perception 9

Languages the languages it knew in life

Challenge 17 (18,000 XP)

Martial Fury. As a bonus action, the dragon slayer wraith swarm can make one weapon attack. If it does so, attack rolls against it have advantage until the start of its next turn.

Swarm. The swarm can occupy another creature’s space and vice versa. The swarm can’t regain hit points or gain temporary hit points except with its Rally the Dead action.

Turn Resistance. The dragon slayer wraith swarm has advantage on saving throws against any effect that turns undead.


Multiattack. The dragon slayer wraith swarm makes two spears attacks, or two rain of arrows attacks.

Spears. Melee or Ranged Weapon Attack: +11 to hit, reach 0 ft., one creature in the swarm’s space. Hit: 40 (10d6 + 5) piercing damage, or 22 (5d6 + 5) piercing damage if the swarm has half of its hit points or fewer.

Rain of Arrows. The dragon slayer wraith swarm looses a volley of arrows at a point it can see within 150 feet of it. Each creature in a 10-foot radius sphere centered on that point must make a DC 16 Dexterity saving throw, taking 18 (4d8 + 2) piercing damage on a failed save, or half as much damage on a successful one.

Rally the Dead (1/day). To use this action, the dragon slayer wraith swarm must have taken damage during the current combat. If the dragon slayer wraith swarm can use this action, it gives itself advantage on attack rolls until the end of its next turn, and regains  100 lost hit points. The dragon slayer wraith swarm may not regain more hit points than its hit point total.


Elven Metshataya

Medium humanoid (elf), chaotic good

Armor Class 15 (18 with mage armor)

Hit Points 150 (20d8 + 60)

Speed 30 ft.

Abilities Str 16 (+3), Dex 20 (+5), Con 17 (+3), Int 17 (+3), Wis 12 (+1), Cha 17 (+3)

Saving Throws Dex +9, Int +7

Skills Perception +9, Stealth +13, Survival +9

Condition Immunities frightened

Senses darkvision 60 ft., passive Perception 19

Languages Common, Draconic, Elvish

Challenge 10 (5,900 XP)

Cunning Action. On each of its turns, the elf can use a bonus action to take the Dash, Disengage, or Hide action.

Evasion. If the elf is subjected to an effect that allows is to make a Dexterity saving throw to take only half damage, the elf instead takes no damage if it succeeds on the saving throw, and only half damage if it fails.

Fey Ancestry. The elf has advantage on saving throws against being charmed, and magic can’t put the elf to sleep.

Sneak Attack. Once per turn, the elf deals an extra 21 (6d6) damage when it hits a target with a weapon attack and has advantage on the attack roll, or when the target is within 5 feet of an ally of the elf that isn’t incapacitated and the elf doesn’t have disadvantage on the attack roll.

Spellcasting. The elf is a 11th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 15, +7 to hit with spell attacks). The elf has the following wizard spells prepared:

Cantrips (at will): chill touch, light, mage hand, true strike

1st level (4 slots): detect magic, feather fall, jump, magic missile, shield

2nd level (3 slots): invisibility, misty step, spider climb


Multiattack. The elf makes three tuuli glaive attacks, or two longbow attacks.

Tuuli Glaive. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 10 (1d10 + 5) slashing damage plus 14 (4d6) thunder damage.

Longbow. Ranged Weapon Attack: +9 to hit, range 150/600 ft., one target. Hit: 9 (1d8 + 5) piercing damage, and the target’s speed is reduced by 10 feet until the end of its next turn. Additionally, the target must succeed on a DC 15 Constitution saving throw, taking 24 (7d6) damage on a failed save, or half as much damage on a successful one.



Gargantuan construct, unaligned

Armor Class 25 (natural armor, shield)

Hit Points  370 (20d20 + 140)

Speed 40 ft.

Abilities Str 28 (+9), Dex 7 (-2), Con 24 (+7), Int 3 (-4), Wis 11 (+0), Cha 1 (-5)

Damage Immunities lightning, poison, psychic; bludgeoning, piercing, and slashing from nonmagical attacks not made with adamantine weapons

Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned

Senses darkvision 120 ft., passive Perception 10

Challenge 25 (75,000 XP)

Legendary Resistance (3/day). If Foesmasher fails a saving throw, it can choose to succeed instead.

Lightning Absorption. Whenever Foresmasher is subjected to lightning damage, it takes no damage and instead regains a number of hit points equal to the lightning damage dealt.

Immutable Form. Foesmasher is immune to any spell or effect that would alter its form.

Magic Resistance. Foesmasher has advantage on saving throws against spells and other magical effects.

Magic Weapons. Foesmasher’s weapon attacks are magical.


Multiattack. Foesmasher makes two warhammer attacks.

Warhammer. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 27 (4d8 + 9) bludgeoning damage plus 10 (3d6) lightning damage.

Thunder Quake (Recharge 6). Foesmasher strikes its warhammer to the ground, creating a wave of thunderous energy. Each creature in a 30-foot cube originating from Foesmasher must make a DC 25 Constitution saving throw. On a failed save, a creature takes  27 (6d8) thunder damage and is pushed 30 feet away from Foesmasher. On a successful save, the creature takes half as much damage and isn’t pushed.

In addition, unsecured objects that are completely within the area of effect are automatically pushed 10 feet away from Foesmasher by the spell’s effect, and the spell emits a thunderous boom audible out to 1 mile.

Legendary Actions

Foesmasher can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. Foesmasher regains spent legendary actions at the start of its turn.

Attack. Foesmasher makes one warhammer attack.

Move. Foesmasher moves up to half its speed.

Hammer Spin (Costs 2 Actions). Foesmasher spins its warhammer. Each creature within 10 feet of Foesmasher must succeed on a DC 25 Dexterity saving throw or take 22 (3d8 + 9) bludgeoning damage plus 7 (2d6) lightning damage and be knocked prone, or half damage on a success and not be knocked prone.



Small fiend (demon), chaotic evil

Armor Class 15 (natural armor)

Hit Points 82 (12d6 + 40)

Speed 0 ft., fly 50 ft. (hover)

Abilities Str 15 (+2), Dex 20 (+5), Con 18 (+4), Int 5 (-3), Wis 9 (-1), Cha 5 (-3)

Damage Resistances cold, fire, lightning

Damage Immunities poison

Condition Immunities poisoned

Senses blindsight 30 ft., darkvision 120 ft., passive Perception 9

Languages Abyssal, telepathy 60 ft. (works only with creatures that understand Abyssal)

Challenge 5 (1,800)


Multiattack. The rullblut makes one attack with its bite. If that attack hits, the rullblut can make one leech attack against the same target.

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 14 (4d6) piercing damage. If the target is a creature, it is grappled (escape DC 12). Until this grapple ends, the rullblut can’t bite another target.

Leech. The rullblut makes one bite attack against a Medium or larger creature it is grappling. If the attack hits, the target takes the bite’s damage, the rullblut latches on, and the grapple ends. While latched on, the rullblut is unable to take any action unless it spends its bonus action to detach itself first. At the start of each of the rullblut’s turns, the creature takes 36 (8d8) necrotic damage and must succeed on a DC 14 Constitution saving throw or become poisoned until the end of its next turn.

If the rullblut takes 10 or more damage on a single turn, the rullblut must succeed on a DC 14 Constitution saving throw at the end of that turn or detach itself from the creature. If the creature or the rullblut dies, the rullblut automatically detaches itself.

Thanks for reading!

Now you’ve got some stuff to kill dragons… and possibly player characters!

If there’s any requests you have or something (or someone) you’d like me to stat, feel free to drop a message below in the comments or contact me at

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Next up I’ll be covering a D&D favorite: beholders! See you then!

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