TEXT: Masks of Nyarlathotep 
  Trail of Cthulhu Conversion notes 
   
  Masks of Nyarlathotep is the all-time great Call of 
  Cthulhu campaign. Monsters, cultists, globe-
  hopping pulp adventures, it has pretty much been 
  the penultimate Cthulhu adventure since 1984. It 
  was only a matter of time before I would run this 
  for my group. 
   
  So keep in mind that this conversion’s purpose is, 
  first and foremost the conversion document for my 
  playing group. I’m a busy guy, and I may forget or 
  omit details that really won’t be relevant for my 
  play group. I don’t know how to make an editable 
  online document (as I’m sure this will be useful for 
  someone else), but I think, in the future, that’s 
  probably the best format for this document. 
   
  This conversion has been done by Stevens Dustin, 
  July 2008 for The Complete Masks of Nyarlathotep 
  published in December 1996. All page references 
  are for that specific document, unless otherwise 
  indicated. Each major section corresponds with 
  each location chapter. 
  Spells 
  Many of the antagonists of Masks are powerful 
  sorcerers, and have laundry lists of spells they 
  know. Of course, not all the spells can be found in 
  both Trail and Call. Some spells that seem 
  somewhat superfluous have been dropped. In the 
  NPC descriptions, the remaining spells not to be 
  found in Trail of Cthulhu are italicized. Their 
  descriptions are below, split into Incantations and 
  Rituals. 
  Incantations 
  Create Zombie 
  Contact Sand Dweller 
  See “Contact Creature Spells” sidebar on p. 113 in 
  Trail of Cthulhu corebook. 
  Contact Yig 
  See “Contact Diety Spells” sidebar on p. 112 in 
  Trail of Cthulhu corebook. 
  Hand of Protection 
  This spell creates a disembodied hand that deflect 
  harm from the caster. He calls upon the Outer 
  Gods, spends 1 Stability point and raises his own 
  hand. The disembodied hand then absorbs 1 point 
  of damage for every point of Stability the caster 
  places in it. Once the caster reaches 0 Stability, the 
  disembodied hand vanishes. 
   
  Stability Test Difficulty: 5 (4 for a Scuffling 
  spend) 
  Cost: 1 Stability plus 1 Stability for every point of 
  damage absorbed. 
  Mists of the Dreamer 
  This spell allows the caster to send Sanity-blasting 
  dreams to his victim. The caster requires a bowl 
  made from “the copper from above,” etched in alien 
  runes, and filled with herbs from the hidden places 
  upon the earth. The caster sacrifices at least 1 
  Stability point and a dram of his blood. The mixture 
  then begins to give off a green smoke that the caster 
  breathes deeply, and hallucinates. 
   
  For every 1 Stability point the caster puts into the 
  dream, the victim must make a d6-point Stability 
  test at Difficulty 5. Therefore, if a caster puts 3 
  Stability points into the dream, the victim makes a 
  3d6 Stability point test. The nature of the dream is 
  always of some Mythos vista or entity. 
   
  Stability Test Difficulty: 5 (4 for a Hypnosis 
  spend) 
  Cost: 1 Stability plus points placed in the dream 
  Quicken Fog-Spawn 
  (page 64) 
  This spell requires a fog-spawn larva and a drop of 
  the caster’s blood smeared on the larva. It is cast 
  within a lightless dense fog. The larva grows into a 
  Thing in the Fog, upon which the caster maintains 
  command of it until 3 hours or 200 feet away. 
   
  Stability Test Difficulty: 5 
  Cost: 8 Stability points 
   
  
  Masks of Nyarlathotep conversion notes 
   
   
   
   
   
   
   
  Page 2 
  Rituals 
  Call/Dismiss Azathoth 
  See “Calling and Dismissing Deities” sidebar on p. 
  120 in Trail of Cthulhu corebook. 
   
  Clutch of Nyogtha 
  In this attack spell, the caster pays the upfront cost 
  of 5 Stability to initiate. Everytime the caster 
  succeeds in a Stability against Stability contest, the 
  victim loses 1d6-1 Health. Once the victim reaches 
  –11 Health, he feels his chest rupture, and his/her 
  smoking heart appears in the caster’s hand. 
   
  Stability Test Difficulty: 5 (4 with a First Aid or 
  Forensics spend) 
  Opposition: The caster engages in a contest of 
  his/her Stability against the victim’s Stability. 
  Cost: 5 Stability 
  Mesmerize 
  This spell allows the caster to mentally dominate 
  the victim, who must have human blood in its 
  veins. The caster pays the cost, and then must 
  succeed at a contest against the victim’s Stability. 
  The caster can then command the victim for a 
  minute for every point of Cthulhu Mythos the caster 
  possesses. The victim must be able to see the 
  caster’s eyes, which will glow malevolently. The 
  victim can only spend 1 point from a general ability 
  for each test while under the command of the 
  caster. 
   
  Stability Test Difficulty: 5 (4 with a Hypnosis 
  spend) 
  Opposition: The caster must succeed in his 
  Stability against the victim’s Stability. 
  Cost: 2 Stability 
  Time: 1 round to cast 
  Tendrils of Quachil Uttaus 
  This spell causes slightly transparent black tendrils 
  to seep from the caster’s fingertips toward the 
  victim. The tendrils steal the life vitality from the 
  victim, transferring it to the caster, making him/her 
  younger. After the initial cost is paid, each round 
  the caster succeeds in the opposition contest, he/she 
  drains 1 Health and 1 Health rating point from the 
  target. The target makes a 5-point Stability test on 
  any successful attack. For each Health rating point 
  taken, the caster grows younger by one week, while 
  the victim ages 1d6+4 years. For every ten years the 
  victim ages, they lose one point in each of their 
  general abilities. The victim turns into a flaking 
  dry-husk once his/her Health rating is completely at 
  0. 
   
  Stability Test Difficulty: 5 
  Opposition: The caster must succeed in a test of 
  Stability versus the target’s current Stability for 
  every attack made. 
  Cost: 2d6 Stability points, which is paid before the 
  first attack. 
  Time: one round to cast, then an attack on each 
  subsequent round. 
   
   
   
  
   
   
  Chapter I: New York 
  New York 
  Our group ran through the New York section using 
  a heavily modified BRP. New York section will be 
  completed once the other sections have been 
  completed. Unfortunately (fortunately?) our group 
  did not finish off Mukunga M’Dari and the 
  Chakota, and I want them to make a comeback. 
  Statistics 
  Bloody Tongue Member 
  Athletics 5, Health 7, Weapons 4 
  Hit Threshold: 3 
  Weapon: -1 
  Mukunga M’Dari 
  High priest of the God of the Bloody Tongue (NYC) 
   
  Athletics 7, Health 9, Scuffling 7, Weapons 6, 
  Stability 7 
   
  Mukunga knows these spells: Bind Byakhee, 
  Contact Nyarlathotep, Create Zombie, Dread 
  Clutch of Nyogtha, Dread Name of Azathoth, 
  Shrivelling, Howl of Pan, Summon/Bind Hunting 
  Horror 
  Hit Threshold: 4 
  Alertness Modifier: +1 
  Stealth Modifier:  +1 
  Weapon: +1 (Lion Claws) 
  Chakota 
  Athletics 4, Health 19, Scuffling 10 
   
  Each bite is a mouth that has attached to the 
  investigator. Keep track of the number of mouths 
  attached. When the investigator attempts to escape, 
  use either Athletics or Scuffling against a Difficulty 
  set by the number of mouths. 
  Hit Threshold: 3 
  Alertness Modifier: +0 
  Stealth Modifier:  +0 
  Weapon: -2 + 1d6 for number of bites 
  Armour: immune to weapons, the Chakota only 
  takes damage from fire, magic and electricity. It can 
  also be suffocated. 
  Stability Loss: +2/+0 for first hearing the 
  Chakota’s cries. 
   
   
  
   
  Chapter II: London 
   
  Penhew Foundation 
  (page 45) 
  • When interviewing Edward Gavigan, Assess 
  Honesty reveals he lies about not knowing 
  Jackson Elias’s London activities. 
  • Archaeology reveals the artefacts have no 
  significance 
  Surveillance 
  • When Gavigan has the investigators tailed, 
  players make Sense Trouble against Difficulty 4 
  to notice cultists shadowing them. 
  • Tailing Gavigan to Tewfik’s shop is a 
  Shadowing against Difficulty 6 test. 
  The Penhew Foundation Building 
  • Athletics or Scuffling against Difficulty 7 
  breaks down the door. Locksmith against 
  Difficulty 4 opens the padlocks. 
  • On a roll of 5 or 6 on a die, men are picking up 
  items from the building in the back. 
  • Tailing the men to the Limehouse docks is a 
  Shadowing against Difficulty 5 test. 
  The Main Floor 
  (page 47) 
  • Library Use in the Penhew Library reveals the 
  existence of a shadowy sorcerous Pharaoh in 
  early history of Egypt. 1-point spend reveals 
  this information in less than an hour. 
  • Architecture 2-point spend reveals hidden 
  panel in the back of Gavigan’s closet. 
  • Evidence Collection reveals worn section 
  before the mummy sarcophagus. 
  • Mechanical Repair reveals mechanism to open 
  mummy case and reveal stairs. 
  The Secret Room 
  (page 47) 
  • Architecture, 
  Mechanical 
  Repair, 
  or 
  Electrical Repair 1-point spend reveals 
  electrical cables, water pipes into secret room in 
  basement. 
  • Archeology reveals the artwork to be Egyptian 
  or proto-Sumerian. Cthulhu Mythos reveals 
  them to show Mythos beings. This causes a 1-
  point Stability test. 
  • Evidence 
  Collection 
  (core) 
  reveals 
  the 
  shipping address to Ho Fong imports on the 
  crates. The statue of the Bloated Woman causes 
  a 1-point Stability test. 
  • Evidence 
  Collection 
  (core) 
  reveals 
  the 
  shipping 
  address 
  to 
  Randolph 
  Shipping 
  Company on the crates. Cthulhu Mythos 
  reveals the statue as Cthulhu (causing a 1-point 
  Stability test). Touching the statue decreasing 
  the difficulty to cast spells by 1 for 24 hours. 
  • Locksmith 2-point spend allows access to the 
  bookcase. Inside are copies of the Livre d’Ivon, 
  G’harne Fragments, and Book of Dzyan. 
  G’harne Fragments reveals that Nyarlathotep is 
  the god of the Bloody Tongue. 
  Gharne Fragments 
  Translation of shards found in North Africa.  
  Skimming provides a dedicated 1-point spend in 
  Archeology or Occult while examining African 
  customs, items or folklore or while visiting Africa. 
  Poring over it adds +1 to Cthulhu Mythos, and 
  bestows an extra 1-point spend in addition to the 
  skim’s 1-point. 
  Book of Dzyan 
  Helena Blavatsky’s tome of Atlantean knowledge.  
  Skimming allows a 1-point Occult spend. Poring 
  over it adds +1 to Cthulhu Mythos. 
  Slaughter in Soho 
  (page 59) 
  Inspector Barrington 
  • Cop Talk (core, floating) reveals the Blue 
  Pyramid 
  is 
  a 
  popular 
  Egyptian 
  club. 
  Furthermore, one victim reported to have said, 
  “Hotep!” before they died. 
  • Cop 
  Talk 
  1-point 
  spend 
  reveals 
  his 
  conversation with Jackson Elias and Edward 
  Gavigan. 
  • An additional 1-point Cop Talk spend for his 
  conversation with Tewfik al-Sayed. 
  The Blue Pyramid 
  • Flattery or Reassurance (core) gets access to 
  Yalesha’s story 
   
  
  Masks of Nyarlathotep conversion notes 
   
   
   
   
   
   
   
  Page 5 
   
  • Tailing the men to Gavigan’s estate is a 
  Shadowing against Difficulty 6 test. Failure 
  results 
  in 
  the 
  cultists 
  ambushing 
  the 
  investigators on the island. 
  The Shop of Tewfik al-Sayed 
   
  • Athletics or Scuffling against Difficulty 6 
  breaks down the door. Locksmith against 
  Difficulty 4 allows entry. 
  • Locksmith against Difficulty 4 opens the desk. 
  1-point Evidence Collection spend reveals the 
  hidden drawer. 
  The Mirror of Gal 
  The mirror has two abilities, both requiring 1 point 
  of Stability for each use: 
  • Scrying. This ability allows the user to see 
  anywhere within 200 miles of its location, but 
  see full description on page 62. 
  • Attacking. When using this ability the caster 
  makes a Stability test against the target’s 
  current Stability. For every point by which the 
  caster succeeds at that test, the target loses 1 
  Health, showing as “heart strain.” Being 
  attacked this way may require a Stability test 
  from the victim. 
  Other Leads 
  The Limehouse Docks 
  (page 63) 
  • Reassurance or Streetwise gets the locals 
  around the Limehouse warehouse to discuss the 
  tough customers and the late night escapades 
  going there. 
  The Ivory Wind 
  • Physics 1-point spend identifies the machine 
  components heading to Ho Fong for reaction 
  motor control, but others are just plain baffling. 
  Rites of the Brotherhood 
  • Arabic points out that Egypt means “Misr” 
  Entrances to the Estate 
  (page 66) 
  • 1-point Evidence Collection spend points out 
  that the bridge can be opened and closed, and in 
  turn trap the investigators on the island, if need 
  be. 
  The Manor House 
  • Architecture or Geology to find the moveable 
  bricks in the fireplace of the great hall. 
  Gavigan’s Country Workroom 
  • Cthulhu Mythos shows that the items in the 
  room are related to the Black Pharoah. 
  • Accounting (core) shows that the fat ledger 
  contains the details of many shipments to Ho 
  Fong and Randolph Shipping. 
  • Evidence 
  Collection 
  (core) 
  finds 
  the 
  unfinished letter to Sir Aubrey. 
  • Occult points out the spell ingredients are 
  magical. Biology identifies the contents of some 
  of the containers (but not all). 
  The Rites 
  (page 69) 
  • Geology shows the stele to be made from 
  unearthly stone 
  • Egyptian Hieroglyphics can reveal that the 
  writing on the stele is a poem praising the Black 
  Pharaoh. 
  Statistics 
  Cultist of the Brotherhood 
  Athletics 4, Health 5, Scuffling 3, Weapons 4 
  Hit Threshold: 3 
  Alertness Modifier: +1 
  Stealth Modifier:  +0 
  Weapon: +0 (club) 
  The Thing in the Fog 
  Athletics 10, Scuffling 13 
   
  The thing cannot be hit, it can only be dispelled 
  with light. Therefore it has no Health, or Hit 
  Threshold. Each tendril that hits causes suffocation 
  damage to its victim (see Trail page 68). 
  Stability Loss: +1 
   
  
  Masks of Nyarlathotep conversion notes 
   
   
   
   
   
   
   
  Page 6 
   
  +1
  herhood of the Black Pharaoh 
   
  Lesser Other God 
  ash and Yko 
  e pseudopod) 
  s: +1 
  The Police 
  Inspector Barrington 
  cuffling 4, Firearms 5, 
  r: +2 
   nightstick) 
  Health 7, Scuffling 3, Firearms 2, 
  ld: 3 
  r: +1 
  k) 
  The Two Scepters 
  Shantak 
  Athletics 6/30*, Health 15, Scuffling 18 
  Hit Threshold: 4 
  Alertness Modifier: 
   
  Stealth Modifier:  +0 
  Weapon: +5 (bite) 
  Armour: -5 
  Stability Loss: +0 
  *flying 
  Edward Gavigan 
  High Priest of the Brot
  Athletics 5, Health 8, Firearms 4, Scuffling 3,
  Weapons 4, Stability 8 
   
  Gavigan knows these incantations: Contact Ghoul, 
  Contact Nyarlathotep, Contact Sand Dweller, 
  Dread Name of Azathoth, Elder Sign, Powder of 
  Ibn-Ghazi, Quicken Fog-Spawn, Shrivelling, Sign 
  of Eibon, Tendrils of Quachil Uttaus (Steal Life), 
  Summon/Bind 
  Byakhee, 
  Summon/Bind 
  Dimensional Shambler, Summon/Bind Hunting 
  Horror, Summon/Bind Servitor of the Outer Gods, 
  Vach-Viraj Incantantion 
   
  Gavigan 
  knows 
  these 
  rituals: 
  Call/Dismiss 
  Azathoth, 
  Call/Dismiss 
  Yog-Sothoth, 
  Contact 
  Nodens, Curse of the Stone, Mists of the Dreamer 
  (Send Dreams) 
  Hit Threshold: 3 
  Stealth Modifier:  +1 
  Weapon: -1 (club), +1 (shotgun) 
   
  Tewfik al-Sayed 
  Athletics 5, Health 6, Scuffling 4, Weapons 6 
   
  Tewfik knows these spells: Body Warping of 
  Gorgoroth, Contact Nyarlathotep, Curse of the 
  Stone, Tendrils of Quachil Uttaus, Summon/Bind 
  Servitor of the Outer Gods 
  Hit Threshold: 3 
  Alertness Modifier: +1 
  Stealth Modifier:  +1 
  Weapon: +0 (club) 
  with names like Dhyigh
  Athletics 7, Health 21, Scuffling 5 
  Hit Threshold: 3 
  Alertness Modifier: -1 
  Stealth Modifier: +0 
  Weapon: +5 (gruesom
  Armour: -5 
  Stability Los
  Athletics 3, Health 6, S
  Weapons 5, Stability 8 
  Hit Threshold: 3 
  Alertness Modifie
  Stealth Modifier: +1 
  Weapon: +0 (weapon,
   
  Constable 
  Athletics 5, 
  Weapons 6 
  Hit Thresho
  Alertness Modifie
  Stealth Modifier: +1 
  Weapon: +0 (nightstic
   
  Both Gavigan and Tewfik possess magic sceptres 
  that when crossed before their bodies, increase their 
  spell-casting ability and defend against spells. The 
  scepters give the caster an increase in 1d6 
  temporary Stability points, and has a pool of 2d6 
  points which absorbs spell attacks meant for the 
  holder of the scepters (example: a spell takes 2 
  Health points, the points are instead taken from the 
  scepters’ pool). 
  A Serpent in Soho 
  Breaking and Entering 
  inst Difficulty 4 
  shows that there is a 
  Knocking at the Door 
  surance convinces 
  oints out that the house smells like the 
  reptile house at the zoo. 
  (page 49) 
  • Athletics or Scuffling aga
  breaks down the door.  
  • Evidence Collection 
  skylight at the top of Miles’ house. The window 
  can be broken in with Athletics or Scuffling test 
  against Difficulty 2. 
  • Credit Rating or Reas
  Ssathasaa to allow the investigators in to buy a 
  painting. 
  • Biology p
   
  
  Masks of Nyarlathotep conversion notes 
   
   
   
   
   
   
   
  Page 7 
   
  ads to the padlocked 
  t the painting’s Inertia of 4. Each 
  smith against Difficulty 3 opens the
  nce Collection to find the 
   find the secret door in t
  The dead bodies cause a 1-point
  erpent People 
  Athletics 8, Health 6, Hypnosis 8, Scuffling 11, 
  eapons 7 
  , Tikkoun Elixir, Voorish 
  ign 
  on: -2 (knitting needle), +0 (bite)+venom
  y 
   6, Scuffling 3, Stability 5, 
  Weapons 5 
   
  The Painting in the Closet 
  • Evidence Collection le
  closet. Locksmith against Difficulty 3 unlocks 
  the padlock. 
  • Upon viewing the painting when it becomes 
  three dimensional, investigators make Stability 
  checks agains
  minute of viewing adds 1 to the painting’s 
  Inertia level. A failed roll sends the investigator 
  into the painting. This causes a 4-point Stability 
  test. 
  The Ground Floor 
  • Lock
   
  • 
  bedroom door. Evide
  Plutonian drug. 
  Basement 
  • Architecture to
  he 
   
  • Assess Honesty (core, floating) shows that 
  Eloise suffers greatly 
  basement. 
  Stability test. 
  Ssathasaa 
  High Priest of the S
  Stability 9, W
   
  Ssathasaa knows the spells Contact Yig, Hand of 
  Protection, Mesmerize
  S
  Hit Threshold: 4 
  Stealth Modifier:  +2 
  Weap
   
  • 
  (Trail page 147) 
  Armour: -1 
  Stability Loss: +0 
  Miles Shiple
  Athletics 3, Health
  Hit Threshold: 3
  Weapon: +0 (meat cleaver) 
  The Derbyshire Monster 
  Lesser-Edale 
  (page 54) 
  • Reassurance or Flattery allows the villagers to 
  open up at the Laughing Horse about the 
  monster 
  • Assess Honesty reveals the constable is worried 
  that he might loose his job if he states that he 
  actually believes in the locals’ gossip 
  • Reassurance or Flattery to interview the 
  families of the victims. 
  Reassurance (core, floating) for John Parkins 
  to admit he thinks that Lawrence Vane was 
  involved. 
  A Visit to Castle Plum 
  (page 56) 
  The Main Hall 
  • Scuffling or Weapons against Difficulty 8 to 
  break down the oak door to the wine cellar. 
  • Scuffling or Weapons against Difficulty 10 to 
  break down the iron doors in the dungeon. 
  The Vicar of Lesser-Edale 
  (page 58) 
  • Reassurance (core, floating) gets the Reverend 
  Stratton to talk to the investigators 
  Assess Honesty (core) reveals that the 
  Reverend is holding something back. 
  • Locksmith (core) to open Stratton’s desk 
  drawer 
  • Flattery or Reassurance for Sarah Bright to 
  admit the Vicar has been acting queerly. 
  Constable Hubert Tumwell 
  Athletics 5. Health 6, Firearms 5, Weapons 4 
  Hit Threshold: 3 
  Alertness Modifier: +1 
  Weapon: +1 (rifle), +0 (nightstick) 
  Reverend Jeremy Stratton 
  Languages 2, Health 4, Stability 5 
  Townsfolk 
  Athletics 5, Health 5, Scuffling 4, Weapons 1 
  Weapon: -1 (torch) 
   
  
  Masks of Nyarlathotep conversion notes 
   
   
   
   
   
   
   
  Page 8 
   
  Lawrence Vane 
  Athletics 3, Health 7, Firearms 4, Scuffling 5, 
  Weapons 4, Stability 5 
  Hit Threshold: 3 
  Weapon: +0 (fencing foil), +1 (shotgun) 
   
  Sir Arthur Gordon Fitzhugh Vane 
  Health 5, Firearms 2, Stability 3 
  Eloise in Werewolf Form 
  Athletics 12, Health 7, Scuffling 4 
  Hit Threshold: 4 
  Alertness Modifier: +1 
  Weapon: +1 (bite, claw) 
  Armour: -1 
  Stability Loss: +0 
   
   
  
   
   
  Chapter III: Cairo 
  Trail of Cthulhu Conversion notes 
   
  
  Masks of Nyarlathotep conversion notes 
   
   
   
   
   
   
   
  Page 10 
   
  NPC and creature stats blocks follow this template, 
  removing unnecessary entries: 
  [Name of NPC/Creature] 
  [List of abilities] 
  Hit Threshold: […] 
  Alertness Modifier: […]  
  Stealth Modifier:  […] 
  Weapon: […] 
  Armour: […] 
  Stability Loss: […] 
   
   
   
  All products and trademarks mentioned here are the properties of their respective owners. Trail of Cthulhu is 
  ©2008 Pelgrane Press Ltd. Call of Cthulhu is © 1981, Chaosium, Inc. The Complete Masks of Nyarlathotep, 
  Third Edition, Reset and Revised is © Chaosium, 1996. The Complete Masks of Nyarlathotep is written by Larry 
  Ditillio and Lynn Willis, along with Geoff Gillian, Kevin A. Ross, Thomas W. Phinney, Micheal MacDonald, 
  Sandy Petersen, and Penelop Love, along with what appears to be a cast of thousands. This conversion is 
  written by Stevens Dustin. 
   
   
  
SOURCE: textdata/thevault/Trail of Cthulhu/Misc/Adventure Conversion - Masks of Nyarlathotep (London Chapter).pdf