Oozes, Slimes, and Gelatinous Cubes 5e- Why They Are REALLY Dangerous

Welcome to our guide to Oozes in Dungeons & Dragons 5e – a comprehensive guide to all things jiggly, gelatinous, and deadly. 

Mindless, unwavering, ever-hungry, Oozes are easily one of my favorite types of monster to throw at a low-ish level party, and a perennial choice for any dungeon master looking to threaten their players with an ignominious and sticky end. 

In this guide, we’ll take a broader look at Oozes as a monster type, examine the four Oozes found within the Monster Manual, and provide some (hopefully) helpful tips for any players unfortunate enough to encounter one.

What Are Oozes in D&D 5e? 

Oozes are a type of monster found throughout dungeons, cave systems, mad wizards’ basements and, of course, the Underdark. 

Alongside dragons, goblins, and shambling skeletons, Oozes (specifically the Gelatinous Cube) are probably among the most iconic monsters in D&D 5e, with a rich history reaching all the way back to 1st edition – Gary Gygax had presumably watched the 1958 film The Blob.  

While there are several different sorts of Ooze with abilities that range from natural camouflage to psychic powers, these creatures share some similar traits. 

Three of the four Oozes in the Monster Manual have the Amorphous trait, which lets them pass through spaces as narrow as an inch wide. Simply shutting the door on an Ooze is unlikely to provide more than a momentary deterrent. 

Two Oozes in the Monster Manual also have Spider Climb, allowing them to drop down onto unsuspecting adventurers from above or escape up a wall if the creature detects that it’s bitten off more than it can chew – or schlorped up more than it can dissolve in its acid jelly, if we’re being pedantic. 

Speaking of acid jelly, all Oozes to some degree or another are composed of highly toxic sludge (of varying potencies), which can corrode metal and organic tissue in moments.

A bold adventurer who plunges their sword into an Ooze is likely as not to pull out a bubbling lump of warped, corroded metal.  

With the possible exception of the Psychic Gray Ooze, all Oozes are essentially mindless, ambush predators, barely distinguishable from an animated plant, that hunt entirely on instinct. 

They are drawn to heat, light, sound, and motion, which can make them easy enough to trick and out-think. However, this single-minded drive to consume and devour also makes them a fundamentally frightening adversary. 

You cannot reason with a Gelatinous Cube. No Ooze is going to stop eating you because you have a high persuasion score. Your relationship to an Ooze is simple: They are hungry, and you’re made of meat. 

Oozes in the Monster Manual 

There are plenty of weird and wonderful Oozes out there – from the terrifying Pudding King and the friendly Glabbagool to the excellent Underdark adventure Out of the Abyss to the seriously troublesome Dragonblood Ooze from Fizban’s Treasury of Dragons, which answers the question “could we give an Ooze a breath weapon?” but never stops to think about whether we should. 

For the purposes of this guide, however, we’ll be sticking to the four (and a half) Oozes found in the Monster Manual.

Hopefully, they can serve as an excellent template for dealing with other, more esoteric varieties and even for DMs looking to homebrew their own. 

Black Pudding

Large ooze, unaligned

Armor Class: 7

Hit Points: 85 (10d10 + 30)

Speed: 20 ft., climb 20 ft.

STR: 16 (+3)

DEX: 5 (-3)

CON: 16 (+3)

INT: 1 (-5)

WIS: 6 (-2)

CHA: 1 (-5)

Damage Immunities: Acid, Cold, Lightning, Slashing

Condition Immunities: Blinded, Charmed, Deafened, Exhaustion, Frightened, Prone

Senses: Blindsight 60 ft. (blind beyond this radius), Passive Perception 8

Challenge: 4 (1,100 XP)

Proficiency Bonus: +2

Amorphous. The pudding can move through a space as narrow as 1 inch wide without squeezing.

Corrosive Form. Any creature that touches the pudding or hits it with a melee attack while within 5 feet of it gets splashed with its corrosive goop for 1d8 acid damage.

Any non magical wooden or metal weapon or piece of ammunition that hits the pudding is corroded, receiving a -1 penalty to damage rolls (after rolling damage the first time) that is both cumulative and permanent. If the penalty ever drops to -5, the weapon is destroyed.  

Spider Climb. The pudding can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Actions

Pseudopod. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) bludgeoning damage plus 18 (4d8) acid damage.

Non-magical armor the target is wearing gets partly dissolved, taking a permanent and cumulative −1 penalty to the AC it offers. The armor is destroyed if the penalty reduces its AC to 10.

Reactions

Split. When a pudding that is Medium or larger is subjected to lightning or slashing damage, it splits into two new puddings if it has at least 10 hit points. Each new pudding has hit points equal to half the original pudding’s, rounded down. New puddings are one size smaller than the original pudding.

Gelatinous Cube

Large ooze, unaligned

Armor Class: 6

Hit Points: 84 (8d10 + 40)

Speed: 15 ft.

STR: 14 (+2)

DEX: 3 (-4)

CON: 20 (+5)

INT: 1 (-5)

WIS: 6 (-2)

CHA: 1 (-5)

Condition Immunities: Blinded, Charmed, Deafened, Exhaustion, Frightened, Prone

Senses: Blindsight 60 ft. (blind beyond this radius), Passive Perception 8

Challenge: 2 (450 XP)

Proficiency Bonus: +2

Ooze Cube. A Gelatinous Cube occupies its entire 10×10’ space. Other creatures can enter the space, but a creature that does so is subjected to the cube’s Engulf and has disadvantage on the saving throw.

Creatures inside the cube can be seen but have total cover.

A creature within 5 feet of the cube can take an action to pull a creature or object out of the cube. Doing so requires a successful DC 12 Strength check, and the creature making the attempt takes 10 (3d6) acid damage.

The cube can hold only one Large creature or up to four Medium or smaller creatures inside it at a time.

Transparent. Even when the cube is in plain sight, it takes a successful DC 15 Wisdom (Perception) check to spot a cube that has neither moved nor attacked. A creature that tries to enter the cube’s space while unaware of the cube is surprised by the cube.

Actions

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 10 (3d6) acid damage.

Engulf. The cube moves up to its speed. While doing so, it can enter Large or smaller creatures’ spaces. Whenever the cube enters a creature’s space, the creature must make a DC 12 Dexterity saving throw.

On a successful save, the creature can choose to be pushed 5 feet back or to the side of the cube. A creature that chooses not to be pushed suffers the consequences of a failed saving throw.

On a failed save, the cube enters the creature’s space, and the creature takes 10 (3d6) acid damage and is engulfed.

The engulfed creature can’t breathe, is restrained, and takes 21 (6d6) acid damage at the start of each of the cube’s turns. When the cube moves, the engulfed creature moves with it.

An engulfed creature can try to escape by taking an action to make a DC 12 Strength check. On a success, the creature escapes and enters a space of its choice within 5 feet of the cube.

Gray Ooze

Medium ooze, unaligned

Armor Class: 8

Hit Points: 22 (3d8 + 9)

Speed: 10 ft., climb 10 ft.

STR: 12 (+1)

DEX: 6 (-2)

CON: 16 (+3)

INT: 1 (-5)

WIS: 6 (-2)

CHA: 2 (-4)

Skills Stealth: +2

Damage Resistances: Acid, Cold, Fire

Condition Immunities: Blinded, Charmed, Deafened, Exhaustion, Frightened, Prone

Senses: Blindsight 60 ft. (blind beyond this radius), Passive Perception 8

Challenge: 1/2 (100 XP)

Proficiency Bonus: +2

Amorphous. The ooze can move through a space as narrow as 1 inch wide without squeezing.

Corrode Metal. Any non-magical weapon made of metal that hits the ooze corrodes. After dealing damage, the weapon takes a permanent and cumulative −1 penalty to damage rolls.

If its penalty drops to −5, the weapon is destroyed. Non-magical ammunition made of metal that hits the ooze is destroyed after dealing damage. The ooze can eat through 2-inch-thick, non-magical metal in 1 round.

False Appearance. While the ooze remains motionless, it is indistinguishable from an oily pool or wet rock.

Actions

Pseudopod. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage plus 7 (2d6) acid damage, and if the target is wearing non-magical metal armor, its armor is partly corroded and takes a permanent and cumulative −1 penalty to the AC it offers.

The armor is destroyed if the penalty reduces its AC to 10.

Variant: Psychic Gray Ooze 

Gray Oozes that survive for long periods of time can begin to manifest greater intelligence than your average Ooze (not that this is saying much).

However, they also begin to awaken latent psychic abilities – a phenomenon more common in Gray Oozes that live near psionic creatures such as mind flayers. 

A psionic gray ooze has an Intelligence score of 6 (−2), as well as the following additional action.

Psychic Crush (Recharge 5–6). The ooze targets one creature that it can sense within 60 feet of it.

The target must make a DC 10 Intelligence saving throw, taking 10 (3d6) psychic damage on a failed save, or half as much damage on a successful one.

Ochre Jelly 

Large ooze, unaligned

Armor Class: 8

Hit Points: 45 (6d10 + 12)

Speed: 10 ft., climb 10 ft.

STR: 15 (+2)

DEX: 6 (-2)

CON: 14 (+2)

INT: 2 (-4)

WIS: 6 (-2)

CHA: 1 (-5)

Damage Resistances: Acid

Damage Immunities: Lightning, Slashing

Condition Immunities: Blinded, Charmed, Deafened, Exhaustion, Frightened, Prone

Senses: Blindsight 60 ft. (blind beyond this radius), Passive Perception 8

Challenge: 2 (450 XP)

Proficiency Bonus: +2

Amorphous. The jelly can move through a space as narrow as 1 inch wide without squeezing.

Spider Climb. The jelly can climb difficult surfaces, including upside down on ceilings without needing to make an ability check.

Actions

Pseudopod. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) bludgeoning damage plus 3 (1d6) acid damage.

Reactions

Split. When a jelly that is Medium or larger is subjected to lightning or slashing damage, it splits into two new jellies if it has at least 10 hit points.

Each new jelly has hit points equal to half the original jelly’s, rounded down. New jellies are one size smaller than the original jelly.

Player Tips: An Adventurer’s Guide To Fighting Oozes

I don’t think I know a single DM who doesn’t have a story in which an otherwise promising campaign was horribly derailed (or almost ended in a TPK) as the result of an Ooze.

Because of their low movement speed, their pathetic armor class, and how hard it is to be afraid of anything that jiggles, I think Oozes tend to get underestimated by newer players. 

This is a mistake. Oozes are nasty pieces of work, and what they lack in anything resembling a brain they make up for by essentially being perfectly evolved to be the apex predator in any low-level dungeon.

Let’s look at exactly why that is and how you as a player can counter some of the Oozes’ natural tools that can turn a breezy romp through a dungeon into a frantic (somewhat embarrassing) reason to roll up a new character. 

Finding the Ooze (Before It Finds You)

One of the nastiest things about Oozes is that by the time you see it coming, it’s already too late.

The famously (almost) invisible Gelatinous Cube usually doesn’t even have to expend any precious energy chasing its prey; it just sits in the middle of a hallway and waits for the next gang of foolhardy adventurers to walk right into it. 

Other Oozes might not be transparent, but they can be just as hard to spot.

Black Puddings and Ochre Jellies, while not exactly camouflaged, can hang from a darkened ceiling or squeeze themselves into a tiny crack in the floor, waiting to drop down on any creature passing below – or perhaps snare the last adventurer in the marching order with a sticky pseudopod.

Gray Oozes are a nightmare as their False Appearance trait makes them completely indistinguishable from an oily pool or wet rock, so long as they remain motionless. 

Signs You Might Be About To Fight an Ooze 

If you’re exploring a dungeon and spot any of the following signs, you may be about to have a close encounter of the Ooze kind. 

  • “It’s clean… too clean”: Oozes hoover up just about any matter that crosses their path as long as it’s not nailed down. This includes insects, spiderwebs, rats, grime and dust, wooden doors, and just about any of the usual detritus that gives a dungeon its decidedly “died in” aesthetic. If you find yourself walking down a suspiciously clean hallway, a gleaming white pile of bones, or realize it’s been over an hour since you saw your last rat, you may want to watch out for Oozes. 
  • Slime: The one thing Oozes do leave behind is a trail of gelatinous slime. If you find yourself following a patch of caustic goop, you may be headed for an Ooze (or possibly Gwyneth Paltrow’s house). 
  • “Floating Treasure”: Even after careful inspection, a Gelatinous Cube can still be completely invisible to the naked eye. However, the metal and bone they consume is not. If you see a skeleton slowly “levitating” down the passage towards you, surrounding by a halo of shiny gold coins, take my advice: go the other way. 

If you’re looking to find an Ooze before it finds you, you can try one or more of the following tricks: 

  • The Ol’ Rock Trick: Whenever moving down an unexplored passage, try throwing small stones ahead of you. If you hear a schplurt rather than a ting, it’s Ooze-fighting time. 
  • The Ten Foot Pole: A similar approach to the Ol’ Rock Trick. In earlier editions of D&D, it was common practice to have the adventurer at the front of the party carry a ten foot pole which, in addition to checking for any nasty, Ooze-related surprises, can also be used to trigger traps and tapped against stone walls to listen for the hollow sound of a hidden door. 
  • Bait: This probably works for just about any unintelligent monster, but Oozes (driven as they are purely by instinct) are especially susceptible. It’s a little unscrupulous, I’ll admit, but bringing along a goat, pig, chicken, goblin prisoner, hapless retainer, or other tasty morsel that won’t be missed to walk about 15 feet in front of the party is a surefire way to avoid any unpleasant surprises. 

Double Trouble 

One of the nastiest little surprises that both Black Puddings and Ochre Jellies bring to the party is their Split reaction. 

Whenever a Black Pudding or Ochre Jelly is subjected to slashing or lightning damage, not only are they considered immune, but they can also use their reaction to divide into two new Oozes.

The resulting creatures have hit points equal to half that of the original Ooze, rounded down, and are considered one size smaller. 

Granted, this is a mistake you only make once, but the fact you now have to fight two Oozes instead of one can be brutal for a party.

So, if you find yourself facing an Ooze, the odds are pretty good that you want to put away your longswords, axes, and anything else that deals slashing damage, or this relatively easy encounter runs the risk of getting twice as hard. 

Bye Bye, Platemail 

Oozes honestly are the bane of martial classes. In addition to rendering any slashing (and lighting) damage your Fighter or Barbarian deals useless, the Black Pudding and the Gray Ooze are both made of such nasty goo that they corrode any metal that touches them in a matter of seconds. 

If you want to avoid your shiny new suit of platemail armor or any of your party’s non-magical weapons getting turned into puddles of bubbling slag, focus on attacking Oozes from range. Reach weapons are your friend. 

Use your characters’ superior movement speed to keep the Ooze at bay, hit it with spells or ranged weapon attacks if possible, and just make sure you don’t let it chase you down any dead ends.

If anyone has a magical weapon and/or magical armor, make sure you put them front and center.