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Monster Vault Preview: Tales of the Valiant presents . . . the gray ooze

Monster Vault Preview: Tales of the Valiant presents . . . the gray ooze

As the creators of the Creature Codex and the Tome of Beasts series, we wanted to give the same love and care for the earliest 5E monsters that we gave to our other monsters. To accomplish that, we noted a few key points we wanted for each monster:

  • Clear Identity. For each creature, we worked to answer, “What makes this creature special? How is it thematically different from other creatures of its type, terrain, or niche?”
  • Unique Features. In clarifying identity, we set ourselves up for better creating unique features. We worked to answer, “What mechanics make this creature different from other creatures? How can we fold its identity into its game mechanics?”
  • Streamlined Statistics. The most obvious change to monsters in Monster Vault comes in our streamlining of the stat block, making a monster’s statistics and features easier to parse at-a-glance. The stat block presented here should give you an idea of some of the changes we made. Compare them to the creature you’ve been using from other source!

Today’s example creature is the gray ooze. In many tabletop RPGs, oozes are distinguished as “the gray one” or “the yellow one.” We felt this was a bit of an injustice to the humble little dungeon jellies, especially those that aren’t cubes.

We created clear identities for each ooze, and the gray ooze gained an identity as living mortar. This allowed us to give them a clearer affinity with stone and gave us the opportunity for new features, like the Solidify reaction where the ooze protects itself by hardening like dried mortar. This added flavor and clearer identity gives GMs more opportunities to use the gray ooze (or any ooze!) in unique and flavorful ways.

Gray Ooze

Fresh mortar glistens on the stone wall. Suddenly, the mortar rises up, snake-like, and lashes out.

Living Mortar. The first gray oozes appeared when curing mortar was accidentally exposed to excess magic near a building site. The oozes have since propagated into their own type of ooze, though some still form when curing mortar is exposed to strong magic. Comprised of the caustic materials that make up mortar, gray oozes can dissolve most material other than stone, but they subsist primarily on animals they can catch.

Stone Affinity. Perhaps due to their origins as mortar, gray oozes have an affinity for stone, particularly worked stone. They are often found in dungeons, stone cities, or old brick buildings, and some longer-lived gray oozes develop minor bonds with the stone they frequent, becoming territorial and protective of it.

Camouflaged Ambushers. When the putty-like ooze lies dormant, a thin crust forms across the surface of its body, making it look like freshly laid mortar. Using this, gray oozes often stretch themselves across worked stone and hide as ordinary mortar to ambush prey.

Gray Ooze                  CR 1/2

Medium Ooze
Armor Class 8
Hit Points 29
Speed 15 ft., climb 15 ft.
Perception 8               Stealth 12
Vulnerable cold
Resistant acid, fire | Ooze Resilience
Immune Ooze Resilience
Senses keensense 60 ft. (can’t sense beyond this radius)


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

Corrode Metal. Any nonmagical 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. Nonmagical ammunition made of metal that hits the ooze is destroyed after dealing damage. The ooze can eat through 2-inch-thick, nonmagical metal in 1 round.

False Appearance. While the ooze remains motionless, it is indistinguishable from ordinary fresh or curing mortar.

Ooze Nature. The ooze doesn’t require sleep.

Ooze Resilience. The ooze is resistant to the grappled and restrained conditions, and it is immune to exhaustion and to the blinded, charmed, deafened, frightened, and prone conditions.

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


Pseudopod. Melee Weapon Attack: +3 to hit, reach 10 ft., one target. Hit: 3 (1d4 + 1) bludgeoning damage plus 7 (2d6) acid damage, and if the target is wearing nonmagical metal armor, the armor is partly corroded and takes a permanent and cumulative −1 penalty to the AC it offers. Armor reduced to an AC of 10 is destroyed.


Solidify. When the ooze is hit by an attack, it can partially solidify its body, reducing the damage it takes by 2 (1d4). If it has taken fire damage since the start of its last turn, the damage it takes is reduced by 3 (1d6) instead. The ooze can’t use this reaction if it has taken cold damage since the start of its last turn.

The Tales of the Valiant roleplaying game comes ever closer! Over 400 classic monsters from 5E history (and some surprises)!
Want to see how else Kobold Press does monsters? Try Tome of Beasts 1 for a giant pile of monsters that are
completely compatible with 5E and the Tales of the Valiant game!

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