OSR: Attack the Sheet

Arnold says you should attack every part of the character sheet. I think it's a great idea.

Here are the obvious examples:

• Most creatures attack HP.
• Rust monsters attack Defense and Attack (by eating weapons and armour). HP too, but that's not why people are scared of rust monsters.
• Stirges attack Constitution (I think? It's been a while. Anyway, they should.)
• Wights and other ghosts attack XP.
• In an abstract way, water attacks armour (try swimming in plate) and items.
• Acid and fire attack items too.
• Total darkness and total panic attack the map (I hide it from the player(s) )

If you're going to attack part of the character sheet in a strange way, give the party a few hints beforehand, or make the consequences less-than-devastating.

Here are a few non-obvious examples:

Two Orcs, Tim Kirl

Paperwork Orcs

Attacks: Gold and Inventory Slots

Orcs were made for warfare, but an organized army still needs someone to track swords, distribute rations, and count things. Paperwork Orcs are the degenerate descendants of a race of quartermasters. Just as common Orcs love to fight, Paperwork Orcs love to write official documents and stamp things. They are as strong as any other orc and just as violent, but they have a deep and ingrained love of money and orderly disorder.

Encounter:
2d10 Paperwork Orcs with a Cave Troll in a shoddy quilted uniform, or some other sufficiently worrying threat. They demand the party purchase permits and travel passes. Each pass costs 1gp and takes up 1 inventory slot. Each time the party passes by the Paperwork Orcs they will demand to see their previous papers and add 1 extra set. The fragile passes are made from bits of wood, parchment, wax, and string.

Soul Leech, chillier17

The Leeches of Paradise!

Attacks: HP

Common leeches are well known cures for blood disorders, stress, fatigue, freckles, and rudeness. The Leeches of Paradise! can only be found in highly magical water sources near primordial ruins, or in caves deep under the earth. They are the ancestors of all modern leeches. They glow blue-white and wriggle. They draw poisons, toxins, and other distempers out of the body at a ferocious rate while excreting a healing mucus into the bloodstream.

Each round a Leech of Paradise! is attached to a creature, the creature heals 1 HP. If a creature is at full HP, it instead gains 1 temporary HP per round. Scars vanish, old aches fade. The character feels warm and lively. If a creature gains temporary HP equal to their normal HP (so, double HP), they explode in a shower of tumors. The leeches then eat the tumors and produce more leeches.

The leeches cannot be cut or bludgeoned (they are too rubbery), but they can be pulled free with a difficult Strength test. The difficulty increases significantly if the target is fully healed and gaining temporary HP. Salt instantly removes the leech but also kills it.

Encounter:
A flooded alchemist's workshop, full of valuable instruments, sunken potions, and leeches. Alternatively, a pool in a primordial forest.

Moth Bat, WaxBottle

Suicidal Bloatbats

Attacks: light sources

They aren't really bats, but some sort of weird moth thing with fur. Maybe they are related to wasps, because they build papery nests high in dry, warm caves. They are about the size of a bat too. And they chitter quietly all day. One or two might go foraging each day, but the main colony rests, waiting quietly in the dark. They nest very deep in caves; they fly very efficiently upwards and descend very rapidly after feeding. On a promising day, at sunset, just after a rainstorm or a flood and when all the plants are as green as they will get, the bloatbats boil out of the cave like a cloud. They can strip a field bare in 10 minutes. Each one will lurch home with a full distended belly. Some don't make it and splatter like rotten fruit.

They fear fire. For most of the year their paper nests are bone-dry, and their eggs are bone dry, and their wings are flammable. A spark could kill them all. In every colony, a few hundred bloatbats are kept full of water, fat and comatose, and ready to strike. At the first glimmer of flame they descend like greasy water balloons, spattering and extinguishing torches, lanterns, and candles. They can tell magical lights from fire, but anything fire-like will earn a salvo of damp bursting moths.

Encounter:
Deep in a cave system, something smacks into the party's only torch. It bursts moistly, and half a dozen more pelt the embers. Above them, something rustles, like a library being turned over with a pitchfork.

Adelheit Herder of Sheep, Beastysakura

The Child-Eating Sheep of Bentham Moor

Attacks: Damage

A legend, but a vivid one. The sheep looks just like an ordinary sheep - grey, fluffy, dull, constantly worried, save that it has no eyes. It lives in a herd of regular sheep, waiting for a shepherd or a predator to attack. The Child-Eating Sheep  traps and enfolds the attacker, devouring it like a sea anemone, and them moves on. The villagers say it has eaten children, wolves, and unwary shepherds. There are dozens of large herds on Bentham Moor, and many sleepless and wind-whipped shepherds.

There are also dozens of Child-Eating Sheep. They are a species of mimic adapted to life in the pasture - on cold nights, they infiltrate a herd, grab a few predators, shepherds, or lambs, and vanish into the fog. Instead of wool, they are coated in a thick and fibrous white slime, which protects them from attack and traps their prey.

Melee attacks that hit the Child-Eating Sheep deal -2 damage per successful hit (so the first hit with a sword would deal 1d6 + Strength Bonus -2 damage, etc.) Arrows and ranged attacks deal a maximum of 1 damage on a hit. The horrible not-wool coating covers weapons, turning them into heavy, useless clubs at best. The Child-Eating Sheep is very small under all that wool - a gulper-eel belly, spider-legs, and an inflatable head. It has a lot of HP. It waits until attackers are thoroughly gummed up and then devours them with its needle-teeth. The not-wool can be removed with olive oil or lots of scrubbing in hot water.

Encounter: there's a missing child in the village. Grab a torch and search the hills! If you can't find the child, at least get revenge.
Alternatively, the villagers like the local Child-Eating Sheep. They keep the wolves away. They just need to be fed a few people, and a bunch of fancy strangers from out of town would do nicely. Let's go for a walk on the moors...

Forest of Vines, hidetheinsanity

Tripwire Vines

Attacks: Movement Speed

A favorite of dryads and druids, tripwire vines are thin grey-green tendrils with soft round leaves. Their sap forms an instant bond with leather, skin, or fur. Step on one vine and it whips upwards, secreting sap, tangling your legs and feet. The sap wears off after a few hours, or if vinegar is poured on the affected area.

Every 10' moved through tripwire vines halves a creature's movement speed.

Encounter: a lonely dryad has planted tripwire vines all over a forest. It spends hours talking to terrified rabbits, deer, and hunters.

Fumblebug

Attacks: Dexterity, Attack ability

A gold beetle the size of a thumb. Drones like a buzz saw in flight. It looks slow and harmless, and it is... mostly. The fumblebug, through some unexplained magic, produces an anti-coordination field. Maybe it causes bubbles of time to slow down or speed up. Maybe it emits nerve-paralyzing pheremones. Whatever it does, it works.

You can't swat the fumblebug. Your swing goes wide. Bite it, and bite your own cheek. Anyone and anything in a 20' radius becomes clumsy, uncoordinated, or out of sync. It's a bit like being drunk. Creatures take a -2 penalty to Dexterity. The range for critical failure increases by 1 (so on a natural 1 or 2). This effect is cumulative. Any attack rolls made in range of 20 fumblebugs are automatically critical failures. The cumulative Dexterity penalty cannot kill a character, but they should move very, very carefully away from the area.

The fumblebug is immune to most attacks a bug-eating predator could use (melee attacks, stomping on it, etc.) It can't be caught either. Its defenses didn't evolve to deal with distant or esoteric threats, so arrows, poison gas, etc. might work. You could probably lure it with food, if you could figure out what it likes to eat.

Encounter: a collapsed civilization tried to breed fumblebugs as a weapon of terror. Unsurprisingly, it failed. Their vast underground breeding complex is full of the things; no predator will approach within half a mile. All the gold and artwork inside is still intact.

Cauldron, Darkest Dungeon

The Mystic Cauldron

Attacks: Rations

A huge iron cauldron on four iron legs. The legs end in little clawed feet, and the cauldron can move at a good running pace if it wants too. A truculent fire elemental floats underneath, keeping the stew warm. The cauldron has an iron lid. If it's opened, the smell is wonderful - it's clearly full of delicious stew.

In a booming voice, the cauldron will ask any person it sees to throw food into the stew. In return, it will allow the person to take a bowl full of stew. One ration or meal equivalent in - one bowl out. After the first bowl, anyone eating it must Save or desire another one, and again after each new bowl. If they become full (about 3 bowls) but still fail their Saves, they'll try to store stew in their boots, their waterskins, etc. The cauldron only provides stew if rations are tossed in first; it refuses to open otherwise and will spray steam at anyone who threatens it.

The stew is an illusion. It vanishes after a few hours, leaving anyone who ate it hungry, and probably very low on rations. The cauldron could feed an army this way, but only in their minds. It can be bargained with (it wants food) and even tricked (you can swear that you eat planks of wood, for example).

Encounter: a harvest festival in a small village has gone terribly wrong. The villagers are tossing their grain and gourds into the cauldron and receiving delicious stew in return. As long as they keep eating, the illusion remains, but they are becoming dangerously emaciated and increasingly hungry.

Abyss Worm, Michael Brack

The Logaworm

Attacks: Items in inventory

Some strange god-touched thing from the dawn of the word. The Logaworm is blind, but it sees by names. It draws named things to itself to consume them. It moves on legs made of swords, trees branches, and bones. Its fat body oozes through tunnels, its blind head dancing with the aurora of raw magic.

If you name something, "a sword", "a rope", "a broken bottle," the Logaworm eats it. It vanishes from your hand and appears in the belly of the creature. It can't eat ensouled things or enchanted items or spells, but everything else is fair game. You'll need to describe items by their function - "the thing that injures", "the thing that is long and bendy and has knots," "the glass thing", and avoid names at all costs. The Logaworm is full of treasure, but it's also full of half-mad skeletons, junk, and slime.

Also, if you point at anything within 30' of the Logaworm, your finger falls off and turns into a larval Logaworm.

Encounter: the PCs are about to embark on a difficult task - a heist, a complex climb, a desperate rescue - when the Logaworm bumbles into them, eating merrily. Ideally, the PCs are in a situation where they'll really want to shout advice and orders to each other; the logaworm doesn't work if nobody talks.