I picked the barghest to examine out of Volo’s Guide to Monsters, recognizing it as a monster that’s been around a long time, but not one I’d ever made use of. Then I read the flavor text. What the what? A monster that only eats goblins? That couldn’t be how this creature was originally conceived.
So I did a little follow-up. Barghests come from Northern English folklore, in which they take the form of huge, black dogs, either possessed by evil spirits or being spirits themselves. The second half of the name is related etymologically to “ghost” and “ghast,” while the first half may mean “city,” “mountain” or even “bear”; no one’s sure. They prey on lone travelers and vagrants, they often have the power to change shape or pass invisibly, and the appearance of a barghest is considered an omen of death.
That’s popular lore. In Dungeons & Dragons lore, barghests began as fiends (as they still are) associated with goblins (as they still are) and often taking a canine shape (as they still do), but the ones that prowled the material plane were the young of those that resided—and ruled their own lands—in Gehenna. The current origin story, in which they’re created by the General of Gehenna to hunt goblins, is a new fifth-edition twist. And, frankly, a preposterous one.
So here’s how I’d interpret the flavor text in the barghest entry: It’s what goblins believe. Everyone’s afraid of barghests, and rightly so—but goblins, for some reason, have developed this myth in which barghests are out to get them specifically, and they’ve concocted the conflict between Maglubiyet and the General of Gehenna as a rationalization of it. I mean, you kind of have to take this approach, or else no one but goblins would ever have reason to be afraid of a barghest. Whereas, personally, I think that player characters and the non-player characters they encounter should absolutely be at just as much risk of a barghest attack as a goblin would be.
Let’s look at the stats. They’re fast—60 feet of movement per turn. Their Constitution is good, but their Dexterity is even better, and their Strength is extraordinary: these are shock attackers and ambush predators. But they’re also smart, even smarter than the average humanoid, to say nothing of the average goblinoid. They have proficiency in Stealth and Deception as well. Not only are they good at hiding and pouncing, they can also present a convincing portrayal of a goblin while in that form.
They’re immune to acid and poison damage, and resistant to cold, fire and lightning damage, as well as physical damage from nonmagical weapons. These creatures are going to be fearless. They have not only darkvision but also blindsight, so they’re going to attack when they have the greatest advantage: in pitch darkness.
While shapechanged into goblin form, they have all their normal stats and features, except their speed and their bite attack. The fact that they have to use an action to transform back into their speedy, chompy true form makes it inadvisable for them to start a fight while in the shape of a goblin. So let’s postulate that they use their goblin form mainly to blend into a community—by necessity, one that tolerates the presence of goblins—and circulate without attracting undue attention. When they’re on the hunt, they revert to their true form. A good rule of thumb might be “goblin form in daylight, true form at night.”
That being said, suppose a barghest is cornered while in goblin form by enemies who’ve realized what it is. Its Innate Spellcasting lets it cast dimension door once per day. Should it use this handy escape hatch to remove itself to a distance where it can use an action to transform into its true form, then return to the fight? Nah. Here’s a better strategy: Use dimension door to escape, then wait a day, then return to true form and begin stalking its enemies that way, when it has the element of surprise. Only if it uses dimension door to try to get away and its opponents somehow manage to find it and chase it down again will it use an action to revert to its true form, and it will do that as soon as it realizes they’re on to it, so that by the time they catch up to it, it’s ready to throw down.
Speaking of Innate Spellcasting, the barghest also gets a daily use each of charm person and suggestion. These are useful fallbacks if the barghest bombs a Deception check while in goblin form, and it can also invoke them if it has a particular need (or desire) to make someone do something against his or her better judgment. The goblin-form barghest is a wicked little troublemaker.
Pass without trace, which the barghest can cast at will, becomes especially useful when it knows it’s being pursued and wants to make a clean getaway. Levitate doesn’t allow its caster to fly per se, only to float, so it’s not super-useful in the barghest’s true form, and in goblin form, it won’t use it if anyone else is watching. Otherwise, it’s good for getting the barghest to places it couldn’t otherwise get to, such as second-story windows and rooftops. Minor illusion is . . . minor.
I said above that barghests are fearless, but they do have reason to shun large areas of open flame: Fire Banishment. If a barghest starts its turn in a large enough fire—at least 10 feet in length or width, such as the wrong side of a wall of fire—there’s a chance that it will be driven back to its home plane. (This doesn’t work with fireball or other fire attacks—the fire has to last long enough for the barghest to begin its turn inside the flames.) Therefore, even though barghests are resistant to fire damage, this is a circumstance they want very much to avoid.
But how does it know when a wall of fire or some other such magical effect is going to appear? It doesn’t. This is a legitimate weakness of the barghest, a way that PCs versed in barghest lore can gain the upper hand over one.
Remember that barghests are intelligent fiends. They know that wizards, sorcerers and druids are the most likely sources of eldritch conflagration. As soon as one such enemy begins slinging damaging spells, area-control spells or evocation spells in general, a barghest will realize that a fire spell could be next, and that spellslinger is going to move straight to the top of its priority target list.
At the start of combat, the barghest will always initiate attack from hiding, if possible. This means either that it’s leaping out from a hiding place (Stealth) or that its target is effectively blinded (most likely by darkness). Unfortunately for the barghest, it has no Multiattack; it has to settle for a bite attack that does two dice of damage. It will never use its claw attack if it can use its bite, and it will never stick around to fight in goblin form (in which it has claw but not bite) if it can get away.
A barghest’s goal in combat is to strike hard and fast, doing the most damage possible. It will rely on its speed and its bite. Its high natural armor class and its resistance or immunity to so many different types of damage, including physical damage from normal weapons, make it indifferent to opportunity attacks. Whomever it wants to kill, it will go straight for, even if that takes it through another opponent’s zone of control.
However, it wants to do damage every round, so even if Maud the druid is its No. 1 enemy, if she’s more than 60 feet away, it’s not going to head her way and stop short when its movement runs out, with no one else to attack within reach. Instead, it will tear through someone else along the way, attacking when adjacent, then using the rest of its movement to keep going.
A barghest will steer clear of any enemy who strikes it with a magical weapon—that’s trouble it doesn’t need. Also, note a couple of types of damage that a barghest is not resistant to: radiant and thunder. Paladins are well-known for dealing both of those. If there’s a paladin on the battlefield, the barghest will always try to be on the opposite side of it, and it may even decide entirely that the fight’s not worth the bother. Clerics and warlocks can also make a barghest think twice by casting spells that do radiant, necrotic or force damage.
Unlike many other fiends, barghests can be killed on the material plane, so when they’re seriously wounded (reduced to 36 hp or fewer), they’re out of there, using dimension door if they have it available, Dodging and moving at full speed otherwise. If their opponents are dealing damage of one or more types they’re susceptible to, they’ll abandon the fight even sooner, bailing out as soon as they’re moderately wounded (reduced to 63 hp or fewer).
Finally, keep in mind that a barghest in goblin form isn’t just making random mischief: it’s conducting reconnaissance. If it sees evidence that the PCs include one of the aforementioned types of spellcasters, it’s going to either refrain from attacking the party at all or—depending on how malicious you want to be—find ways to distract or neutralize those casters before it makes its move.