DRIDER: Monster Conversion - AD&D 1e to Call of Cthulhu 5e.

Closer to what I'm thinking of than a search for Drider brings up.
Thanks to Arachne, Dante, Dore and Wikicommons for this.

Unless you've already ported Lolth into your Call of Cthulhu campaign (in which case I'm interested in what it looks like now), Driders are 'just' spidertaurs - and the spider part isn't even a spider, really.

Driders aren't a species to themselves, and will be known by chosen/given names or possibly by a local/legendary name for spidertaurs (eg. Jorogumo).

In this conception, Driders have nothing to do with Lolth or the Drow; are no more common in Japan than anywhere else, and have no association with Atlach Nacha or Leng unless they themselves seek it - they can expect no particular favour for similarity of form.

No silk (this is 1st edition AD&D), no Drow spells. Unless you want to.

Drider,  Venom Bloated Composite Multipede.

You become a Drider because you find a way to bind yourself to a giant spider-like body in order to extend your lifespan to study the foul & forbidden, because the Mi-Go do elective/involuntary surgery on you, or because you are struck by a curse. 

You will live well beyond a human lifespan without loss of vigour, as long as you do not succumb to violence or the venom your monstrous body produces. This is ideal for continuing your awful studies, to carry out the will of the Mi-Go, or to prolong your suffering.

Blood is now the perfect food for you, although you can subsist on anything high in protein and/or iron, as long as it’s at least semi-liquid. If you like, you can continue to eat human food for appearance and pleasure, but it is not compatible with your radically altered internal organs and body chemistry - it won't sustain you long term, but it won't do you any harm.

You have fangs, retractable or otherwise, in your human mouth to deliver venom and drain blood. It seems reasonable that you may be able to open your jaw much wider than you used to.

While other configurations are possible, the Drider you are expecting is a spidertaur. The spider section only superficially resembles an arachnid, and could easily have four or a dozen legs as eight. They can be hairy, scaly, chitinous, slimy - anything you like.

The human portion looks as it did in its previous life, although swollen, puffy, discoloured with venom, eventually leaving a permanent mark despite frequent purges (see below). Venom accumulates in the humanoid part at 2 POT/ day, and is uncomfortable to excruciating, with accompanying emotional and mental distress. 

At 12 POT + the Drider will be violently irritable, even destroying allies and important research. 

At 16 POT + it takes a poison attack per day for d6 temporary STR, CON, INT & DEX damage. Once venom is below 16, characteristics recover 1 point per day.

At any time it can purge by biting, ‘milking’ its fangs, or directly tapping its sacs with a blade or syringe - some will have spigots permanently inserted to make this easier. There is bound to be a nefarious text somewhere claiming the venom is the source of the Drider's longevity.

A Drider is composed of conventional matter, albeit unconventionally and incompatibly. They are natives of mundane space/time.

Humanoid Part (when operating on a human scale, eg. embroidery, throwing rocks, picking pockets)

STR 3d6 (10.5)     SIZ 3d6 (10.5)     DEX 3d6 (10.5)     Damage bonus nil

Arachnoid Part 

STR 3d6+6 (16.5)     CON 4d6+6 (20)     SIZ 4d6+12 (26)     INT 2d6+6 (13)     POW 2d6+6 (13)

DEX 3d6+6 (16.5)

Hit Points av. 28       Damage Bonus +2d6     Move 8 

Weapons:

• Human weapons, base % + Humanoid DEX, no db. No particular reason a Drider wouldn't use a bow-and-arrow, and no reason it wouldn't use a revolver either. 
• Grapple, base % + Humanoid STR & DEX. Against human scale targets only; if successful, will Bite on the next round. 
• Bite, automatic if Grappled. 1d4 hits + venom (the Drider can use some or all of its accumulated venom) and/or blood drain (d4 STR per round until dead or set free).
• Crush, 50%, damage = db. A Drider is big enough to crush multiple adult human-sized targets, one for every 12 whole SIZ points its spider body has. If able to jump or drop onto targets, it's 1 for every 10 SIZ.

Armour: 2 points on the humanoid part; 4 on the arachnoid. It can choose to wear armour, if available.

At 0 hp or lower, the Drider is dead (unless blown to pieces, disintegrated etc.), but will continue to fight on for three more rounds before finally coming to a stop, even if it’s on fire. It can only make crush attacks & is working on instinct only. The humanoid part flops and flails. 

The same applies if the humanoid part is decapitated, but not if major organs are destroyed. This is not common knowledge - the Drider may not know.

Skills: Dodge (DEXx2 + INT); Climb 90% (but can climb any surface & hang from ceilings); Jump (STR+DEX); Hide 60%; Sneak 75%; Sense Vibrations 40%; Cast Horrendous Shadow 75%.

Spells: Any average Drider will know 0-7 (d8-1). These are unlikely to be directly Mythos related, unless the Drider's state is due to Mythos intervention. 

If a Drider has POW 12+, it knows one spell per point over. 

Habitat: not too far from a plentiful supply of blood, with space for books and experimental equipment.

Sanity loss: 0/1 to see a Drider’s horrendous shadow; 1/1d6+1 to see a Drider; 1/d10 to realise that you have become one.

MUCALYTIC: Monster Conversion - Fighting Fantasy to D&D adjacent and Call of Cthulhu 5e.

It is a MUCALYTIC and you must fight it!
(John Blanche)

From Out of the Pit (p. 84): SKILL 8, STAMINA 9, 2 Attacks, Average Intelligence; stinks so bad you lose 2 STAMINA, and if it hits you three times in a row you get a lungful of its fatal breath.

In the Sorcery! series, you can encounter them in Khare and in Mampang, where they will try to pull the same trick on you - pretending not to be able to hear well or talk above a mutter, then give you a lungful when you lean in.

They left an impression on me.

Mucalytic for D&D adjacent.

Armour Class +2     Hit Dice 4/5    Move 75% Normal Human     Save Fighter 4/5     Morale 8

• The stench of a Mucalytic is as foul as and has the same effect as that of a Troglodyte or a stinking cloud (your choice).
• The breath of a Mucalytic is deadly poison (save or die, or save or 2d6/2d8 hits: your choice), but it has no ranged attack.
• It attacks with 2 blows for d4 or d6 each; it can fight two opponents at once if it wants.
• If both blows hit a single victim, they are grabbed and pulled close - the Mucalytic breathes on them at the start of the next round.
• Anyone slain in a Mucalytic lair will be broken down into a repulsive slime within 3d6 turns if not retrieved. Only their bones remain.
• Mucalytics have Average Intelligence, and can speak & understand other languages.
• It seems reasonable for Mucalytics to share spaces with oozes, slimes and jellies, and to be found in BECMI Black Hag entourages.

Mucalytic, Trunk-Snouted Ascetics of Decay.

In some dismal and filthy wallow, the Mucalytic sits in darkness, murmuring and muttering who knows what to itself. Its indistinct croaking whispers tantalise with the enlightenment found in degradation and decay: "Come a little closer, step into the sacred mire, and receive the Blessing and the Secret."

Mucalytics are composed of conventional matter, being creatures of the mundane space/time continuum. They can see in the dark, and don't like the sun or running water - nothing supernatural, they just dry out/ wash away their beloved slime.

Of course a Mucalytic will pretend to be Chaugnar Faugn or one of its avatars/representatives if that conclusion is drawn; wouldn't you?

STR 2d6+6 (13)     CON 4d6 (14)     SIZ 3d6+10 (20.5)     INT 3d6 (10.5)     POW 3d6 (10.5)

DEX 2d6+6 (13)

Hit Points 17-18    Damage Bonus +1d6     Move 6

Weapons: 

• Sloppy Bash 45%, d4 + db
• The Mucalytic can strike twice in a round, against either one or two opponents. If both attacks hit a single target, it will Grapple them (STR/SIZ vs. STR/SIZ).
• The Blessing 100% if Grappled; poison breath equal to curare (POT 25, immediate onset, muscular paralysis & respiratory failure). The Mucalytic takes no other action.
• Those killed or incapacitated in the Mucalytic's lair will receive the Secret, becoming one with the slime and ooze within 3d6x10 minutes. Only their bones remain, beautifully stripped and clean.
• The stink of a Mucalytic and its surroundings is so rank, all appropriate roles are penalised by 10% unless proper precautions are taken.

Armour: 2 points of muck-plastered hide. 

Skills: Hide 75%; Fool You Twice 35%; Cthulhu Mythos min. INTx2; unaffected by penalties due to slippery, greasy or waterlogged conditions.

Spells: A Mucalytic can expend magic points one-for-one in an attempt to overcome those of a target; success means the victim will approach and bow their head in readiness for the Blessing.

Otherwise, if INT and POW are both 13 or greater, the Mucalytic knows d6 spells - usually Contact spells, and those dealing with extrasensory communication.

Habitat: sewers, storm drains, toxic waste dumps, slimy caves, silted ruins, blighted water meadows - you get the idea. 

Sanity Loss: 0/1d6 to see a Mucalytic; 1/1d6+1 to survive the Secret; 0/1d4 to smell a Mucalytic having encountered one before and failing to overcome it (esp. if you saw someone receive the Blessing).

Commentary.

In converting to D&D adjacent, I'm fortunate that the OotP entry describes them as being 'about the size of a bear'. A SKILL of 8 converts to a 4-5 HD monster according to a conversion document I've seen, so the BECMI Black and Grizzly Bear fit the bill quite nicely.

2d6 Morale & Misery: A Work-in-Progress Subsystem.

Because I think adventures are miserable and scary, and that PCs don't come heroic to the table, amongst the things I wanted is/was some kind of subsystem for that.

Ideally, to satisfy my personal homebrew design conceits, it draws on a limited pool of old school source material, so it's not going to be elegant game design. That said, I also point to the excellent games Best Left Buried and Mothership, which already have dedicated mechanics for this, as well as owing a debt to this post (a good source for Relief and Suffering alternatives, too) by Spwack, which really helped bring it together for me.

This is not meant to be a mental health simulator, and Misery as a mechanic doesn't actually mean you're/your character is sad. 

I'm writing with dungeoneering horror fantasy in mind, but it could easily be tweaked to work for other play styles and settings. It should also bolt onto lots of other systems, as it doesn't have an absolute link to (say) levels or ability score bonuses.

Morale & Misery.

The implied Morale score of a BECMI or B/X PC is 12, because they are exempt from Morale checks. 

Eating away at your Morale of 12 is your Misery, which is the accumulation of fear, horror, grief, emotional damage, dread, shock, and suffering over your adventures. 

Adventurers can start with 0 Misery, if they're well-adjusted, keen to right wrongs, and eager to upend plots against the common weal. Or if they have no idea of what's waiting for them out there.

Otherwise, they start with 2 Misery - this can be the fruit of your tragic backstory, or from your Dark Secret, or because you must be in some dire straits if your best/only option is to go down into the dark, looking for treasure.

Tiers of Misery.

• 0-1: no problem; go about your business as normal - seeking Relief might actually be counterproductive.
• 2-5: it is up to you whether you seek Relief or take on Suffering. At this tier, Misery might drop back to 2/0 when you're between adventures.
• 6-10: on any failed Misery Check, you must immediately (or as soon as practical) seek Relief or take on Suffering.
• 11-12: you can/will do nothing except seek Relief or take on Suffering until your Misery is taken down to 5 or lower. If you fail a Misery Check at this tier, you are Enfeebled and Spent till you can be taken somewhere safe to start your recovery (magic or fantasy healing might help in situ, if that's a thing in your setting).

The Misery Check.

• You can call it a Morale Check if you like, and I sometimes do, because it's different for PCs than for monsters.
• Roll 2d6; you want to roll over your current Misery to pass (so you can't on 12 Misery).
• Rolling a 2 is always a fail, even if Misery is 0 or 1.
• You make a Misery/Morale Check whenever circumstances would call for (for example) a SAN check or save vs. fear. You can also use for tests of courage and resisting temptation. 
• If you fail, you suffer the situational consequences. If you pass, you can carry on.
• Sometimes the consequence is to gain Misery, and a pass might decrease it.

Sources of Misery.

These things can give you +1 to +3 Misery, and you normally get to make a Misery Check as a save.

The following are meant as suggestions; nothing is adamantite, and how you rate and apply them will be dependent on the tone of the game, the setting, and the characters. You can get used to some of the Sources, so that they have no effect in future - this is not always a good thing.

• night out in the cold & wet
• being in a dungeon/wilderness
• just being a 1st level adventurer
• having a Dark Secret
• lithotomy
• surprised by a corpse, a mangled corpse, a monster
• your life is threatened by another
• the first time you have to kill
• reduced to 0 hp (or equivalent state in your game/system)
• the same circumstances as would trigger a Morale Check in monsters
• hungry & thirsty
• trapped/imprisoned
• no chance of surrender/mercy
• robbed
• pinned down and unable to escape/retaliate
• Tired, Exhausted or Spent
• Encumbered or Overburdened
• a really big monster, even just evidence of its presence
• the undead, generally
• supplies run out/spoiled/taken
• difficult moral/emotional choice
• sanity-blasting cosmic horror
• cursed
• lost
• excommunicated
• price on your head
• plague, volcano, earthquake, tsunami, cave-in etc.
• bad omens
• buried alive/wake up in a morgue
• signs of the apocalypse
• alone
• horrifying revelations
• studying forbidden lore
• failure
• betrayal (both directions)
• living under tyranny
• bereavement
• left for dead
• poverty
• addiction/withdrawal
• guilt/shame
• disappointment

Relief & Suffering.

These are the two ways of buying down Misery. Either can be taken immediately to reverse a failed check, but some are more appropriate for downtime activities.

Relief buys down 1, 2 or (exceptionally) 3 Misery. As with Sources, you can get used to a form of Relief and it stops working for you (some have this attribute incorporated).

• Drink and/or drugs. Take 3 times in a row or 5 in total to become Addicted (as the Suffering, but you don't reduce Misery for it). Costs money, could get you into other trouble.
• Retreat. The more you buy down, the more reckless the retreat and vulnerable you are. The only attacks your allowed to make are against those in the way of your escape, friends and innocents included.
• Hot meal, clean clothes and a good night's sleep in the warm and the dry.
• Pampering. A bit of personal self-care, or a full spa day/weekend. Takes time and costs money.
• Asceticism. Gets more effective the longer & more often you do it, until it peaks and effectiveness diminishes but time needed continue to increase.
• Placebo. The first one works, whatever it is, but each one afterwards needs you to pass a Misery Check for it to work. Fail 3 times in a row or 5 in total to realise it was always useless (+2 Misery).
• Faith. A source of comfort, but also mechanically/narratively similar to Drink/drugs, Asceticism and Placebo.
• Rational Explanation/False Scare. If you are convinced that it wasn't what you thought it was, you can buy down the specific Misery you took.
• Charity. Can also be part of Faith; buying down your Misery by actually buying it down. Includes other good works and acts of kindness.
• Swoon. Covers staggered/shaken, involuntary jump back, dropping your weapons, dizzy spell, actual fainting.
• Lash out. Against the Source of Misery, against the nearest thing, living or not. Probably includes going berserk.
• Bloodletting. In a quasi-medieval grimdark fantasy setting, you can get this done professionally (possibly as a Placebo). Being cut in combat might work for you. Equally, it might be someone else's blood that you need to see flow.
• Defend. Shorter term version of Pacified/Demoralised (see below). Boss fights might be exempt, but might not.
• Not being in a dungeon/wilderness. Just go home for a bit.
• As an option, some characters might be able to relieve some Misery - I'm thinking bards, priests (not necessarily the mace-and-plate cleric), druids (in vanilla form) and (why not?) Heroes and Superheroes and paladins; possibly based on Charisma, Wisdom or relative experience.

Suffering is a longer term consequence, but buys down 3 or 6 Misery. You can get Sufferings removed, but that takes time - during which they have a significant mechanic/narrative effect.

• Change Path. You abandon your current class/profession/passion and take up another to pursue; your previous abilities and experience are blocked.
• Doom Seeker. Dig out the AD&D Cavalier class (or better yet, Mockman's comic version) - their combat honour code, you act like that now. Some people think you're really amazing because of it; everyone else thinks you're a monster.
• Addiction. No matter what else you do, feeding your addiction is your primary goal.
• Nervous Collapse. If you do not take to your bed or a sanatorium for a long rest cure, you are Enfeebled.
• Insomnia/Nightmares. Whichever you think is most appropriate - the effect is largely the same - Misery Checks every night or progressively Tired/Exhausted/Spent.
• Crushing Self-doubt. Your confidence in your own abilities is broken, reroll every success unrelated to your recovery.
• Swords into Ploughshares. You turn your back on the adventuring/investigating life. Maybe take up beekeeping, or retreat to the cloister. You can combine this with Asceticism, Faith and Pacified, if you like.
• Ruled by Omens. You spend all the time and money you can on charms and oracles. When the signs are not auspicious, you Suffer Crushing Self-doubt.
• Debauched. You might think you're okay and you're just enjoying a surfeit of Relief. 
• Bad Luck. All your rolls are at -1; this eliminates any bonuses from Ability Scores or abilities, but does not affect existing penalties - they do not get worse.
• Lost in a Fog. Reroll all successes related to Intelligence and Wisdom.
• Wretched. Reduce Charisma by twice as many Misery you buy down (ban or modify this one if Charisma doesn't affect much or is a dump stat in your game). While Wretched, any Relief buys down Charisma 1-for-1. 
• Pacified/Demoralised. The former appears to be a deliberate ethical/moral choice, but the effect is much the same - you will not make attack actions, only defensive. This might save your life.
• Relapse. Take a Suffering you've previously had and recovered from. It probably buys down less than it did, or it's more severe than last time.
• Sycophancy. You try to curry favour from the most important/powerful, available/immediate figure, whether friend or foe. You are effectively charmed whenever the situation presents itself.
• You Monster! You are now able to buy down Misery by inflicting the equivalent on others, you horrible bastard.

Other Methods.

These are not so much things you can do as things that can happen to bring down your Misery.

• Successfully completing an adventure (as defined by the game).
• Gaining a level (or equivalent in unlevelled systems).
• The feeling of security possessing a magical item brings.
• The feeling of security being an expert in your field brings.
• Having a certain amount of wealth.
• Not dying.
• Vicarious victory.
• Becoming a Hero (4th) or Superhero (8th) should probably reset your Misery to 0 or 2 (though it might not get rid of Sufferings), as well as rendering some Sources superfluous.
• Divine intervention.
• Discovery and exploration.
• Falling in love (you can't just declare it; otherwise it's just a specific Sycophancy, and is creepy).
• Recovery from injury and disease (including by beloved others).
• Going to see the Great Clown perform (doesn't work for the Great Clown).

Commentary.

This probably works as presented, but I don't think it's necessarily finished. And it certainly hasn't been play tested, so I'm not even sure that 12 points is enough for an extended game.

As well as the implied D&D PC Morale of 12, I looked to Fighting Fantasy, a 2d6 system.

In House of Hell, your FEAR is the maximum you can bear before you die of heart failure. However, it's tied up in the puzzle of the book and the ratings are all over the place (being threatened with a knife is as scary as witnessing a climactic demonic transformation, for example). You need an absolute minimum of 8 to survive to the end (so can be doomed from the start), and the only chances to recover from FEAR are right at the beginning (when you might have 0 FEAR anyway), and when you have a false scare (which only cancels out the point you just gained).

Beneath Nightmare Castle uses WILLPOWER as a SAN stand-in, and degrades by a point every time you have to Test it - you lose your mind and the game if you hit 6. It is stated that 'you are already tired' (you've been ambushed and imprisoned), which is why you lose your mind at 6 or lower, implying - I think - this would not be the case if you were in a better starting state.

Keep of the Lich-Lord uses RESOLVE, with a loss if you fail a Test, a gain if you succeed. I've not played this book, so I don't know how it feels as a mechanic.

Vault of the Vampire (and its sequel) has FAITH, but this works more like the ability of a paladin-like character than a universal mechanic.