Lumbering, stinking, grasping — an unnatural horror formed of rotten branches, bones, moss, and strange, misunderstood magics. Fire cannot hurt it, and lightning only makes it stronger. Get too close, and it drags you inside its huge, shapeless body, into a mass of razor sharp thorns, strangling vines, and choking mold.
If you die in its embrace, your body will become a part of the heaving, reeking mass: just another part of the Shambling Mound.
Today, we’re going to be talking about one of the most interesting, unique, and genuinely underrated monsters in all of D&D 5e. It also happens to be one of my favorites. It’s time to talk shambling mounds. We’re going to be going over how they work, where they come from, how to fight them, and, for all you dungeon masters out there, we’re going to talk about how to incorporate a shambling mound into your own campaigns.
What Is a Shambling Mound?
Found in desolate marshland, swamps, and choking jungle, shambling mounds are slow, ponderous, all-consuming masses of animate vegetation and organic matter that devour anything and everything in their path.
Created by a combination of lightning, fey magic, and swamplands, these omnivorous plants are ambush predators, using their natural camouflage to surprise their prey. Though amorphous and ever-shifting, their rotten bodies often form into a featureless “head” that rests atop their vast, ponderous bulk.
- STR 18 (+4), DEX 8 (-1), CON 16 (+3), INT 5 (-3), WIS 10 (+0), CHA 5 (-3)
- Armor Class: 15 (natural armor)
- Hit Points: 136 (16d10 + 48)
- Speed: 20 ft., swim 20 ft.
- CR (XP): 5 (1,800 XP)
- Senses/Languages: Blindsight 60 ft. (blind beyond this radius), Passive Perception 10; Languages: —
- Proficiency Bonus: +3
- Size: Large
- Type: Plant
- Alignment: Unaligned
- Damage / Condition Resistance / Immunity: Damage Resistance (cold, fire), Damage Immunity (lightning), Condition Immunity (Blinded, deafened, exhausted)
- Skills: Stealth +2
- Saving Throws: —
Lightning Absorption. Whenever the shambling mound takes lightning damage, instead of being damaged, it is healed for a number of hit points equal to the damage dealt instead.
Multiattack. The shambling mound makes two slam attacks. If both attacks hit a Medium or smaller target, the target is grappled (escape DC 14), and the shambling mound uses its Engulf on it.
- Slam. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.
Engulf. The shambling mound engulfs a Medium or smaller creature grappled by it. The engulfed target is blinded, restrained, and unable to breathe, and it must succeed on a DC 14 Constitution saving throw at the start of each of the mound’s turns or take 13 (2d8 + 4) bludgeoning damage. If the mound moves, the engulfed target moves with it. The mound can have only one creature engulfed at a time.
Shambling mounds have been around since the very first edition of D&D, and as such, they’re a bit… weird. For a large, zombified clump of partially decomposed vegetable matter and sodden dirt, the shambling mound is a remarkably stealthy opponent — perhaps due to its natural camouflage.
It’s not quick with a walking (and swimming) speed of just 20 feet, so we’re to assume that it largely prefers to hunt by surprise, attacking, grappling, and engulfing its prey before the startled creature (or adventurer) has time to react. Still, with a reach of just 5 feet, shambling mounds are definitely limited to stationary targets or perhaps those who stumble upon it unprepared; any party that becomes aware of the mound is going to be able to either avoid it or engage it on their terms.
A party of adventurers that chooses (or is forced) to fight a shambling mound, however, may find themselves in for a series of nasty surprises as there’s plenty about this frankly bizarre monster that doesn’t work how you’d expect. The immediate instinct of any adventurer faced with a plant is to use fire, to which the mound is resistant (same with cold damage) because of how completely soaked through it is.
Then, if anyone tries lightning damage (less likely but a very unpleasant surprise if it happens) the mound is going to be healed, which is a truly horrible moment for any party that’s already having a tough time. Nevertheless, I think the shambling mound’s affinity for lightning can also be a weakness. If powerful electrical impulses heal the mound, it stands to reason that they’d be attracted to it. A shambling mound that is targeted with lighting damage will probably stop whatever it’s doing and move toward the source, hoping for more delicious galvanizing energy.
Granted, a party will likely figure out the shambling mound’s various tricks and quirks in a matter of a round or two, but in 5e, where your average combat lasts just four rounds, that’s definitely enough for a shambling mound to do some serious damage.
Speaking of damage, let’s talk about the very old-school way that the shambling mound hits. The old “if both attacks hit, then the monster does even more automatic nasty stuff” is a very retro form of monster design that, frankly, punishes bad luck and can very quickly result in PC death.
Basically, the mound advances, directing both of its attacks against the nearest potential prey it can detect with its blindsight. Then, if both attacks hit, it completely envelopes the target — meaning they are restrained, blinded, taking damage, and suffocating.
The suffocating is especially bad because, although a character can hold their breath for a number of minutes equal to 1 + Constitution modifier (minimum 30 seconds), a creature that “runs out of breath or is choking, … can survive for a number of rounds equal to its Constitution modifier (minimum of 1 round).”
This means that a low-constitution character absorbed by the mound has an incredibly short life expectancy if the mound engulfs it. Then, because the automatic damage against an engulfed target doesn’t stop when you enter death-save territory, an unconscious character inside a shambling mound is going to automatically accrue death-save failures every round. The result is that an encounter with a shambling mound can go from good to bad to catastrophic very quickly.
A Dungeon Master’s Guide to Shambling Mound Encounters
Shambling mounds are one of my favorite monsters for a few reasons. Firstly, they’re weird and unexpected, which makes them dangerous; they’re a learning encounter for the players. Secondly, they can either make for an interesting solo challenge (perhaps as part of a random encounter) or fit into a larger dungeon or string of encounters. Thirdly, they don’t have to be monsters at all; thanks to their low speed and relatively simple mechanics, shambling mounds can also serve as an environmental hazard.
Take the five-room dungeon method of encounter design, for example. A shambling mound is a great choice for a first room or guardian encounter — something for the PCs to figure out how to get past rather than an intelligent enemy that needs to be fought. Finding a way through an area where one or more shambling mounds are present can make for an exciting change of pace if your party has so far just cleared rooms of enemies.
I also think the lore (or lack thereof) surrounding shambling mounds and their creation is interesting. According to the Monster Manual, a shambling mound is created when “lightning or fey magic invigorates an otherwise ordinary swamp plant,” giving it a strange new necrotic life — although its creature type is still “plant” rather than undead, monstrosity, or aberration.
Personally, I like the idea of lightning that strikes areas suffused with fey magic creating shambling mounds. The appearance of such a mound is a telltale sign of an incursion by the fey folk (who are much scarier in my home game than the 5e monster manual would have you believe). Also, druids who dwell in marshlands and practice swamp magic will call down lightning to create shambling mounds to protect their groves.
Other races with a connection to the land — like myconids or firbolgs — might create or harness shambling mounds, corralling them into natural chokepoints to defend their villages, keeping them in place with regular meals. The mounds are stupid, but they aren’t mindless and will likely stay near to wherever they are regularly fed — especially if any exits or ways past them are beyond their 60 feet of blindsight vision.
Of course, there are other ways to deploy this monster as well.
Lorghoth the Decayer
One of the classic introductory adventures for 5e is the opening to Curse of Strahd, the notoriously brutal and unforgiving 1st-level module called Death House. In addition to a specter, a gang of cultists, and several other brutal undead foes, players in this adventure will eventually have to contend with a “half-submerged pile of refuse” that the cultists have dubbed Lorghoth the Decayer.
This is, of course, a shambling mound. Lorghoth is kept happy and healthy behind its portcullis at the very bottom of the basement of the Death House, fed regularly by the cultists as part of their adulation for the darklord Strahd himself.
Describing Shambling Mounds
When I run shambling mound encounters, I like to emphasize the amount of death, rot, and decay inherent to these monsters. Skulls and bones jut out through the leafmold; scraps of armor, broken spears, and weapons stick out through the vines and foliage.
They smell of sweet, earthy decay mixed with the sharp tang of ozone — lightning never really leaves a shambling mound — and perhaps most terrifying of all, they attack in complete silence, broken only by the creaking and snapping of branches and the rustle of leaves.
Whatever role that a shambling mound takes in your campaign — whether you want to give the local cult to a death god something to worship or just make the nearby swamp feel especially nasty — your players should be in for a dangerous, terrifying time.