Monday, February 23, 2026

OSR Integration of Mayfair Games Role Aids Demons & Bloat Games Survive This! Vigilante City Rpg

 "In Demons, you met the lords of the Infernus. now learn the dark secrets of these evil fiends, their methods most foul and how they taint the world of mortals. Learn too, how they might be sought out and destroyed. The world has faced no greater threat than the palpable evil that is... Demons! ~ The Demons II source pack includes: * An 80 page game master's book detailing how demons act and how they taint the world around them; * A 48 page book of demonic adventures; * The 32 page "Razor of Righteousness", a tome which discusses how demons may be recognized, hunted and eradicated; * The "History of the Endeavor", a book of notes describing the Cabal, a brotherhood of ambitious thaumaturgists; * A new character class, the Inquisitor,his habits and techniques; * Expanded information on Slayers, Thaumaturgists and half-demons; * Descriptions of the Gates, the demons' pathways to the plane prime; * Information on the ways of the demon-worshiping cults; * Dozens of demon-wrought magic items and adventure inspirations!"


Gemini said

Yes, you absolutely can play SURVIVE THIS!! Vigilante City with Mayfair Games’ Demons line.

Because both systems share a "D&D DNA," they are mechanically cousins. Vigilante City is an OSR (Old School Renaissance) system based on the d20 SRD (specifically a mix of White Box and 5E), while Mayfair’s Demons was explicitly designed as a "Role Aids" supplement for AD&D 2nd Edition.

Here is how you can make them work together:

1. The Mechanical Bridge

  • Stat Compatibility: Both games use the standard six ability scores (Strength, Dexterity, etc.). You can drop a demon from Mayfair’s Denizens of Infernus directly into Vigilante City with almost no math.

  • Armor Class (AC): Vigilante City typically uses Ascending AC (higher is better), while Mayfair’s 1990s books used Descending AC (lower is better).

    • Quick Fix: To convert a Mayfair demon to Vigilante City, subtract the Mayfair AC from 20. (e.g., a Mayfair AC 2 becomes a Vigilante City AC 18).

  • Hit Dice (HD): These function identically. A 5 HD demon in Mayfair is roughly a Level 5 threat in Vigilante City.

2. Thematic Synergy

Vigilante City is inspired by 90s cartoons like Batman: The Animated Series and TMNT, which often featured "supernatural" or "occult" episodes. Using the Mayfair books allows you to:

  • Urban Horror: Turn your street-level supers game into a supernatural thriller where a gang is backed by an actual Duke of Hell.

  • The "Mystic" Class: Vigilante City has a Mystic class that fits perfectly with the ritual magic and "Infernicum" lore found in the Mayfair boxed sets.

  • Villain Motivation: Mayfair's demons are categorized by "Sins" (Og, Vecheron, etc.), which provides great flavor for a gritty city's criminal underworld.

3. Potential Speedbumps

  • Power Levels: Mayfair’s higher-tier demons (Lords/Princes) are designed to challenge high-level AD&D wizards. Vigilante City is "street-level" and caps at Level 10. Be careful not to accidentally TPK (Total Party Kill) your heroes with a demon that has "Save or Die" abilities, which are common in Mayfair’s older material.

  • Saving Throws: Vigilante City uses a simplified saving throw system. When a Mayfair monster calls for a "Save vs. Spell," just use the character's standard Vigilante City saving throw.


In SURVIVE THIS!! Vigilante City, the Thaumaturgist isn't just a "wizard"—they are the urban occultists, the back-alley exorcists, and the scholars of forbidden lore. They represent the "Mystic" archetype found in 90s comics (think John Constantine or Dr. Strange).



Since you are looking to integrate Mayfair’s Demons, the Thaumaturgist is your essential bridge, as they are the only class equipped to handle the Infernal mechanics from those supplements.


The Thaumaturgist NPC / Class Overview

The Thaumaturgist relies on Intelligence and Wisdom. They are physically frail compared to a Vigilante or Mutant, but they control the battlefield through reality-bending effects.

Core Stats & Mechanics

FeatureDetail
Hit Diced4 per level (Low survivability)
Primary AttributeIntelligence (for spell learning) and Wisdom (for casting)
Armor/WeaponsRestricted to light weapons (knives, canes, small pistols)
SavesBonus vs. Magic and Mental effects

Key Class Abilities

  • Spellcasting: Unlike traditional "Vancian" magic, Vigilante City often uses a Usage Die or Spell Points. For a Thaumaturgist, casting is taxing. If they fail a casting roll, they may suffer "Arcane Backlash" or "Stress."

  • Occult Knowledge: They can identify supernatural entities (like Mayfair's Lords of Pit) on a successful INT check.

  • Ritual Casting: Given enough time (and often expensive components), they can cast powerful spells beyond their current level. This is the perfect mechanic for banishing a Mayfair Demon.

  • Sense Magic: The ability to "see" the ley lines and magical residue left behind by supernatural crimes.


Integrating with Mayfair Games' Demons

To make the Thaumaturgist feel "authentic" when facing Mayfair-style threats, consider giving them these specific NPC traits:

1. The Banishing Arts

In Mayfair's Demons, entities are often tied to a "True Name" or a specific "Sin." A Thaumaturgist NPC should have the ability to research these weaknesses.

House Rule: A Thaumaturgist can reduce a Mayfair Demon's AC or Magic Resistance by 2 if they spend 1d4 rounds chanting a specific counter-incantation.

2. The Cost of Magic

In Vigilante City, magic is gritty. If an NPC Thaumaturgist fails a spell while fighting an entity from the Mayfair books, use the Mayfair "Possession" tables. Instead of just losing the spell, the demon might begin to seep into the caster's mind.

3. Summoning Specialty

The Thaumaturgist is the primary way players will interact with Mayfair’s "Infernicum." They act as the "Quest Giver" or the "Information Broker" who knows exactly which circle of hell a specific villain escaped from.


Example NPC Seed: "Old Man Miller"

  • Role: Occult Bookshop Owner / Retired Thaumaturgist

  • The Hook: Miller knows the players are being hunted by a Vecheron Demon (from Mayfair). He can’t fight it himself (he only has 4 HP), but he can enchant the Vigilante's brass knuckles to deal "Holy Damage" for 24 hours.

In SURVIVE THIS!! Vigilante City, the Slayer is the premier supernatural hunter. While the Vigilante class fights muggers and the Mutant fights supervillains, the Slayer is specifically optimized to track, endure, and destroy the things that go bump in the night—making them the perfect foil for Mayfair’s Demons.


The Slayer Class Profile

The Slayer is a high-action, high-survivability class. Think of them as the "Blade" or "Buffy" of your campaign: highly trained, incredibly focused, and often carrying a heavy burden of forbidden knowledge.

Core Statistics

  • Hit Dice: d10 per level (Front-line durability).

  • Primary Attributes: Strength (for melee/staked weapons) or Dexterity (for crossbows/evasion) and Constitution.

  • Combat Progression: High. They gain bonuses to hit more rapidly than most other classes.

  • Saving Throws: They receive significant bonuses against Fear, Paralysis, and Death Rays (essential for surviving high-level Demon spells).


Key Class Abilities

The Slayer’s toolkit is designed to even the odds against creatures that are faster and stronger than humans.

1. Monster Hunter (The "Favored Enemy")

At 1st level, the Slayer chooses a category of monster (e.g., Demons, Undead, Lycanthropes).

  • The Bonus: They gain a $+2$ bonus to damage and a $+1$ bonus to AC when fighting these specific foes.

  • Mayfair Synergy: If they choose "Demons," this bonus applies to all entities from the Denizens of Infernus or Lords of the Pit books.

2. Supernatural Awareness

The Slayer can "smell" or sense the presence of the supernatural within 30 feet. This isn't precise (they won't know it's a Level 4 Vecheron immediately), but they know something "wrong" is nearby. This prevents them from being surprised by demonic ambushes.

3. Hardened Mind

Because they deal with cosmic horrors, Slayers are harder to break. When a Mayfair demon uses a Fear Aura or a Charm effect, the Slayer rolls their saving throw with Advantage.

4. Specialized Armory

Slayers are proficient with "Old World" weapons that bypass many demon resistances:

  • Silvered blades.

  • Blessed crossbow bolts.

  • Vials of Holy Water (which, in Vigilante City, can be used like grenades).


Playing a Slayer against Mayfair Demons

When integrating with the Mayfair system, the Slayer becomes the party's "Tactical Lead."

  • The Breach: Mayfair demons often have high Magic Resistance. The Slayer is usually the only one who can deal reliable physical damage while the Thaumaturgist works on the banishment ritual.

  • Identifying the Sin: Using their Occult Lore skill, a Slayer can identify which "Sin" a demon represents (per Mayfair lore), allowing the party to exploit its specific behavioral weakness.

Slayer Archetypes

StyleFocusSuggested Gear
The Relic HunterFinding ancient artifacts.Whip, Silver Dagger, Trench Coat.
The Tech-ExorcistUsing "Science" to fight Hell.UV Lamps, EMP Grenades, Shotgun with "Salt" rounds.
The Chosen OneInnate supernatural speed.Dual Katana, Leather Armor, High DEX.

Pro-Tip: If you are using the Mayfair "Possession" rules, the Slayer should have a unique trait where they can "Internalize the Demon." Instead of being possessed, they can trap the entity's influence in their own mind for $1d6$ rounds to protect their teammates, though they take psychic damage in the process.

 To create a Warrior Demon for SURVIVE THIS!! Vigilante City that feels like it stepped out of a Mayfair Games supplement, we need to blend 90s grimdark aesthetics with OSR mechanics.

In Mayfair’s Demons lore, Warrior Demons are often the "Brutes" or "Myrmidons" of the Infernicum—beings of pure martial malice who serve a specific Prince or Duke.


Warrior Demon (Infernal Myrmidon)

A towering, soot-stained humanoid with skin like cracked basalt. It carries a jagged "Soul-Cleaver" and breathes the faint scent of ozone and rotting copper.

StatValue
Hit Dice6d8 (Approx. 27 HP)
Armor Class17 (Ascending) / 3 (Descending)
Move30 ft.
Attacks2 × Soul-Cleaver (1d10+3) or 1 × Gore (1d6 + Knockdown)
Saving Throw12+
AlignmentChaotic Evil (The Sin of Wrath)
XP650

Special Abilities & Traits

  • Infernal Resistance: Takes half damage from non-magical, non-silver weapons. (In Vigilante City, "Advanced Tech" weapons like lasers may bypass this at the GM's discretion).

  • Aura of Malice (Mayfair Mechanic): Any hero within 10 feet must make a Save vs. Morale/Fear. On a failure, they suffer a $-2$ penalty to hit as their courage falters in the presence of pure hate.

  • Blood-Scent: The Warrior Demon has Advantage on tracking checks against any target that has current HP below its maximum.

  • Relentless: If reduced to 0 HP, the demon makes a CON check. On a success, it stays at 1 HP for one more round of frantic, desperate attacks before dissolving into ash.


Integrating Mayfair Lore

To make this more than just a "monster," assign it a specific Sin from the Mayfair books to dictate its behavior:

  • The Sin of Pride: The Warrior Demon will refuse to use cover or stealth. It wants you to see it coming. It will target the strongest-looking PC first.

  • The Sin of Envy: It will prioritize attacking the PC with the coolest "Super Power" or the flashiest gear, attempting to break their items first.


Combat Tactics for the GM

  1. The Charge: It begins combat with a Gore attack. If it hits, the target is knocked prone.

  2. The Cleave: It uses its two Soul-Cleaver attacks on the prone target with Advantage.

  3. The Dissolve: When defeated, it doesn't leave a body. It leaves a scorched "shadow" on the pavement and a faint whispering sound—a hook for your Thaumaturgist to investigate.


Suggested Loot/Drops

If the players manage to kill it without magical means, they might find:

  • A Cracked Infernal Core: Can be sold to an occult shop for $500 or used by a Thaumaturgist to power a ritual.

  • The Soul-Cleaver: A heavy weapon. In a human's hands, it deals 1d10 damage but requires a Wisdom Save every day to avoid becoming "Vindictive" (a personality flaw).

To merge the street-level grit of Vigilante City with the infernal hierarchy of Mayfair Games’ Demons, this table balances mundane urban crimes with escalating supernatural horror.

The "Hell on Earth" Random Encounter Table (d100)

d100Encounter TypeDescription
01–15Street Grime2d4 Thugs shaking down a local shopkeeper. They are twitchy; one has a strange "Mark of the Pit" tattoo.
16–25The OmenA murder of crows circles a specific skyscraper. A Thaumaturgist senses a "Thin Spot" in reality nearby.
26–35Infernal MyrmidonA Warrior Demon (see above) is hunting a "Sinner." It’s currently tearing the roof off a bus to get to them.
36–45Possessed VictimA beat cop is acting strangely, lifting a patrol car with one hand. A Minor Demon from Mayfair's Denizens has taken hold.
46–55The Black MarketA van selling "Power Enhancements." It’s actually a front for Grand Polyphon; the drugs are distilled demon ichor.
56–65Slayer’s TrailYou find a discarded, silver-plated bolt and a pile of foul-smelling ash. A Slayer NPC is nearby and may be wounded.
66–75The Sin of EnvyA localized "Aura of Envy" hits the party. PCs must Save vs. Spells or spend 1 round trying to steal a teammate's gadget/weapon.
76–85Hell-Hound Pack1d4+1 Shadow Hounds (Treat as Wolves with +2 AC and Fire Breath). They are tracking the party's scent.
86–95The Ritual6 Cultists in a subway tunnel attempting to summon a Duke of Hell. The air is freezing and smells like sulfur.
96–99The HeraldA pale man in a suit (Polyphon's Avatar) approaches. He offers a "Contract" to solve the players' current biggest problem.
100The BreachA literal portal to Infernus opens. 1d6 Warrior Demons emerge. The sky turns a bruised purple.

How to use this table effectively:

  • The "Slow Burn": Early in the campaign, stick to the 01–35 range. As the players gain levels and interfere with the Princes of Hell, add a $+10$ modifier to your rolls to push them into the more "Demonic" encounters.

  • Environmental Cues: Whenever you roll a "Supernatural" result (36+), describe a shift in the city. The neon lights flicker, the shadows grow longer, or the stray dogs in the alley start whimpering in unison.

  • The Mayfair Connection: If you roll a Possessed Victim (36–45), use the Possession rules from the Mayfair boxed set. It turns a standard combat into a high-stakes rescue mission where the heroes have to knock out the host without killing them.


Encounter Spotlight: The "Sinner" (Result 26–35)

When the party encounters a Warrior Demon hunting a "Sinner," don't make the victim a "good guy."

The Twist: The victim is actually a rival mob boss or a corrupt politician. The players must decide: Do we save a "human" monster from a "literal" monster?

To truly capture the Mayfair Games Demons vibe in Vigilante City, you need a villain who feels like a cosmic manager of evil. In the Mayfair hierarchy, Amdosias (the King of Demons) or one of his Grand Princes would be the ultimate threat.

Given your urban setting, Grand Polyphon, Prince of the Mind, is the perfect fit. He doesn't just smash buildings; he corrupts the city's infrastructure, media, and sanity.


Grand Polyphon: Prince of the Mind

Role: Lord of Lies and Subversion

Domain: The Court of the Mind (Infernus)

Vigilante City Context: Polyphon operates through "The Cabal"—a secret society of corrupt politicians, corporate CEOs, and media moguls. He rarely fights directly, preferring to frame the heroes for crimes they didn't commit.

StatValue
Hit Dice15d12 (Approx. 100 HP)
Armor Class22 (Ascending) / -2 (Descending)
Move40 ft. (Teleports at will)
Attacks2 × Mind-Blast (3d6 Psychic) or Touch of Insanity (1d4 Wisdom Drain)
Saving Throw5+
AlignmentLawful Evil (The Sin of Deceit)

Legendary Abilities

  • Master of Disguise: Polyphon can appear as any human perfectly. Not even a Slayer’s supernatural awareness can pinpoint him immediately; it only tells them "the air feels oily."

  • Mass Possession (Mayfair Special): Once per day, Polyphon can attempt to possess an entire crowd (up to 50 people). This creates a "zombie" horde of innocent civilians that the heroes must deal with without using lethal force.

  • The Silver Tongue: Any PC attempting to resist a command from Polyphon must roll their Wisdom Save with Disadvantage. He knows exactly what you're ashamed of.


The Plot: "The Static King"

In a Vigilante City campaign, Polyphon shouldn't appear as a giant winged demon until the final act.

  1. Phase 1: He appears as Julian Vane, a billionaire philanthropist funding a new "Crime-Free" surveillance network.

  2. Phase 2: The surveillance tech actually broadcasts a low-frequency infernal signal that makes citizens prone to paranoia and rage.

  3. Phase 3: When the heroes break into his penthouse, Vane sheds his skin to reveal a multi-faced, translucent entity—the Prince of the Mind.

Weaknesses (The "Mayfair Hook")

Per the Denizens of Infernus rules, Polyphon is bound by his specific Sin.

  • The Truth Paradox: Polyphon cannot speak a direct truth. If a Thaumaturgist traps him in a Circle of Salt and forces him to state a simple, objective fact (e.g., "The sky is blue"), he takes 5d6 damage and is banished back to the Infernus.


Comparison: Mayfair vs. Vigilante City

FeatureMayfair (AD&D)Vigilante City (OSR)
Power LevelHigh (Requires +3 weapons)Epic (Requires a Level 10 Party)
Main ThreatSoul Corruption / Level DrainStress / Reputation Damage
Defeat MethodDivine InterventionInvestigation + Ritual Banishment

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