B/X Monsters A to Z: Gray Ooze

 Slime time! Our monster today is the gray ooze from the Basic Set. Despite the sheer bulk of the black pudding, the gray ooze may well be the most dangerous of the slimes and oozes I've covered so far.

Gray ooze is said to look like wet stone, making it difficult to see. One might well expect a bonus to surprise opponents because of that, but apparently it's only a flavor detail here, not something to be represented mechanically. That might be just as well, considering...

The monster's stats don't immediately impress: its AC of 8 makes it easy to hit, and 3 Hit Dice, while a lot for Basic-level parties, doesn't take too long to whittle down. If you can stay alive long enough, that is, because this thing is bringing some serious hurt. A gray ooze secretes powerful acid that inflicts 2-16 points of damage on a successful attack. After that, it does 2-16 points per round automatically, in addition to automatically destroying non-magical armor. (Magical armor can hold out for a full turn.) In other words, if the ooze hits someone, and doesn't kill him outright, it has a good chance of finishing him off soon after. A tough fighter or dwarf might have a number of rounds about half his level. If it hits someone with a d4 or d6 HD, the odds are even less encouraging. 

Like most of its slimy cousins, gray ooze is fearless and relentless, with Morale 12. It's even slower than most of them, though, creeping at a glacial 10' (3'). Its mobility seems almost solely for the purpose of crawling to a new ambush point once the prey get wise to its location; for the purposes of a single encounter, it might as well be immobile. Even a heavily encumbered party can easily escape from it, though they might be leaving a dead or dying comrade behind. If they bother to take shots at the monster from afar, they'll quickly find their slings and arrows will harm it, and can probably dispatch it quickly... assuming it doesn't have some crack or crevice to slither into and escape. Fortunately, only one is encountered at a time.

Gray ooze is immune to damage from fire or cold, but can be harmed by weapons and lightning. It seems rather an odd detail, something never likely to be relevant or even discovered during actual play, but I guess after a harrowing first encounter with a gray ooze, players might actually try flinging fireballs and lightning bolts at the next one from a safe distance. Once corroded, twice shy.

Gray ooze is essentially the glass cannon of the slime world. For low level parties, this monster is a straight-up killer if they don't finish it off before it lands a successful attack on someone. Higher level parties have a good chance to come out of the encounter without any deaths, but likely at the cost of a big chunk of someone's hit points and maybe armor too.

It isn't explicitly stated, but as no duration or method of neutralizing the acid is given, the most reasonable inference is that damage to living creatures and/or magic items only continues as long a the ooze is alive and actively secreting acid. Once the ooze is dead, significant damage ceases. 

Because I'm a very weird person, I've always held my own notions of the relative consistencies of the various slime and ooze monsters. In my mind, gelatinous cubes are solid and resilient, like Jell-o, black puddings are thick and gooey, green slime is like snot, and ochre jellies are, well, like grape jelly, semi-solid and sticky. Gray oozes, in part because of that "seeping horror" description in its rulebook entry, I've always imagined as being the most fluid, somewhere in the neighborhood of molasses or maple syrup. 

Would I change anything about the gray ooze? At first, I thought maybe the damage could be reduced, but that's kind of its thing, what makes this monster special and dangerous. I think the only tweak I'd make would be to give it a hefty bonus to surprise, reflecting the fact that it appears nearly identical to wet stone. 5-in-6 is a bit extreme, but feels right. Of course, that's only for parties who blunder right in without testing patches of glistening stone with a pole; those cautious sorts would detect it automatically. It would thus serve almost as a sort of trap to keep players on their toes rather than a standard monster encounter.