TEXT: STANDARD RULES
  ๏ Armor: Subtract the listed hit point factor from the damage 
  roll.
  ๏ Dodge: An investigator may only dodge the first bullet shot 
  at him in a round. If dodging, an investigator may also parry, 
  but not attack.
  ๏ Impales: On a d100 result equal to 1/5 or less of the player’s 
  skill with a pointed weapon an Impale occurs.
  • Roll for damage twice on an Impale.
  • Some Mythos creatures are immune to Impales.
  • Hand-to-hand weapons stick in the target on an impale 
  and the investigator may spend another round making 
  another weapon skill roll to free the weapon. Removing 
  the weapon deals no damage.
  ๏ Parry: Parry equals the weapon skill and may only be 
  performed once per round. The target of the parry is 
  declared at the beginning of the round.
  ๏ Surprise: Those surprised act at 1/2 DEX. Extreme surprise 
  affords no attacks for the surprised party in the first round,
  ๏ Knock-Out Attacks: Using unarmed or blunt attacks, roll 
  damage as normal and compare the result against the target’s 
  HP on the Resistance Table. If the attacker is successful, the 
  target takes 1/3 damage and is knocked out for several 
  rounds. On a defender 
  success, the target takes 
  full damage. A successful 
  First-Aid or Medicine roll 
  immediately wakes a 
  target.
  • Most Mythos 
  creatures may not be 
  knocked out.
  • Humanoid creatures 
  may be knocked out 
  at Keeper discretion.
  ๏ Thrown Weapons: If an 
  investigator throws an 
  object add half of his 
  damage bonus to the 
  damage done. See also the 
  Throw Skill.
  ๏ Two Weapons: Two melee weapons may be held, but only 
  one attack and one parry may be made per round, as usual.
  FIREARM TYPES
  ๏ Automatic Weapons: Weapons capable of this may fire in a 
  burst on the shooter’s DEX score. For each shot fired in the 
  burst, raise the attacker’s chance to hit by five percentiles up 
  to double. Roll d100 once for all shots. If the attack roll is a 
  success roll the die type equal to the number of shots (6 
  shots = d6). The result of this roll determines the number of 
  hits. Only the first bullet impales.
  • If multiple targets are spread across a field of fire, the 
  shooter’s chance to hit is not modified. Each target is 
  rolled for separately to hit. The shooter allots how 
  many bullets head toward each target.
  • If a single target or multiple targets are within a narrow 
  cone of fire (i.e. coming down a hallway or tunnel), 
  increase the shooter’s chance to hit, but no more than 
  double.
  ๏ Revolvers: A fully loaded revolver may go off accidently. 
  Resolve this with a Luck Roll. To avoid this completely, load 
  only five shots.
  ๏ Shotguns: Double-barrel shotguns may fire both rounds 
  simultaneously at DEX in one round, one barrel at DEX and 
  at half DEX in the same round or one barrel each in 
  different rounds. Depending on gauge, a pump-action may 
  fire once or twice a round. Any semi-automatic fires once or 
  twice in a round.
  FIREARM ACTIONS
  ๏ Point-Blank Fire: If the distance to the target is equal to or 
  less than the shooter’s DEX in feet, the shooter’s chance to 
  hit is doubled.
  ๏ Extended Range: An Investigator may attack at up to double 
  a weapon’s base range at 1/2 the normal chance to hit, triple 
  at 1/4 chance, quadruple at 1/8 chance, etc. At such range, 
  damage may be lessened as the bullet slows.
  ๏ Big Targets: Big things are easier to hit. For monsters over 
  SIZ 30 or more, every 10 SIZ above SIZ 30 adds 5 
  percentiles to an attacker’s base chance to hit with a bullet, 
  thrown object or shotgun round. Point-blank and extended 
  range modifiers apply.
  ๏ Aiming: Bracing or using instruments to aim allows the 
  shooter to fire once in a round at half DEX. The effect is to 
  double the point-blank and base ranges.
  ๏Reloading: Allow one 
  combat round to load two 
  rounds or shells into any 
  handgun, rifle or shotgun. 
  Allow one combat round to 
  exchange a clip. Allow two 
  rounds to attach a machine 
  gun belt.
  •In one round, it is possible 
  to chamber one round and 
  fire that shot at half DEX.
  ๏Two Handguns: One 
  person may hold and fire two 
  handguns during a combat 
  round. Use the Unaimed 
  Shots rule below.
  ๏Unaimed Shots: Unaimed 
  fire allows twice the number 
  of attacks per round listed for the weapon. Reduce the 
  shooter’s chance to 1/5 normal. If there is more than one 
  target, determine randomly who is hit. Impales occur 
  normally. Given laser sight aid and training, and Handgun 
  60% and above, increase the chance to hit to normal.
  ๏ Malfunctions: If the roll is equal to or higher than the 
  weapon’s malfunction range (mal), the weapon cannot fire.
  • Consider this a dud round for revolvers, bolt-action 
  rifles and double-barreled shotgun.
  • Consider this a jam for automatic, semi-automatic, 
  pump-action or lever action weapon. Fixing the jam 
  takes 1d6 combat rounds and a successful Mechanical 
  Repair roll or a weapon skill roll for the firearm type 
  jammed. The owner can keep trying until successful or 
  until a result of 96-00 is rolled (in which case the 
  weapon is ruined).
  Call of Cthulhu
  Basic Role Playing System Combat Reference
  All references to the Basic Role Playing System, the game of Call of Cthulhu and other materials herein are Copyright Chaosium, Inc.
  COMBAT SEQUENCE
  ๏1st DEX Cycle: All drawn and aimed firearms 
  fire in DEX order, highest to lowest. If DEX 
  scores are tied, roll d100, the lowest goes first.
  ๏2nd DEX Cycle: This time include:
  • All hand-to-hand attacks.
  • All 2nd firearm attacks.
  • All 1st firearm attacks if the firearm wasn’t 
  initially drawn or readied.
  • Other Actions (First-Aid, Spell-casting, etc.)
  • Firearms with a third shot fire at half DEX.
  
  HAND-TO-HAND
  ๏ Kick: May parry. May only rarely knock out. 
  ๏ Head Butt: May be used in cramped quarters. May knock 
  out.
  ๏ Fist/Punch: May parry kicks and head butts. May knock out.
  ๏ Grapple: If a grapple check is successful and not neutralized 
  (via a STR vs. STR Resistance Table roll, and note that 
  additional attackers combine their STR),   the attacker holds 
  the target and may thereafter may exercise one of the 
  following options:
  • Immobilize the Target: By overcoming the target’s STR 
  with his or her own STR using the Resistance Table. 
  With a success the target is held indefinitely until the 
  grappler attempts another action.
  • Knock Down the Target: If used, this action is 
  automatically successful.
  • Knock Out the Target: in a first or later round. See the 
  knock-out rule, p. 60.
  • Disarm the Target: The initial Grapple roll acts as a 
  Parry. Thereafter, the second successful Grapple roll 
  may seize the weapon or the weapon hand.
  • Physically Injure the Target: If successful the target 
  receives 1d6 damage. This may be repeated each round.
  • Strangle the Target: Beginning the round the intention 
  is stated, the target begins to asphyxiate as per the 
  Drowning rules. This continues in subsequent rounds. 
  The attacker requires no further Grapple rolls.
  ๏ Martial Arts: If the successful attack roll is less than the 
  Martial Arts skill, the attack does double damage.
  PHYSICAL INJURY
  ๏ Stun: A knock-out attack, electrical shock, fall or other injury 
  may incidentally stun an investigator for 1d6 combat rounds. 
  The investigator may only parry or dodge for the duration. 
  When a stun occurs is left to the Keeper’s judgment and may 
  or may not include a loss of HP.
  ๏ Shock: If, from a single wound, the investigator loses half or 
  more of his current hit points, the player is forced to roll the 
  investigator’s CON x5 or less on d100 or the investigator 
  falls unconscious.
  ๏ Unconsciousness: When an investigator has 1 or 2 HP, he 
  automatically falls unconscious until HP rises to 3 or the 
  Keeper determines a time for the investigator to awaken. 
  Time may heal the wound enough for the investigator to 
  stagger away or a First-Aid or Medicine roll may help as well.
  ๏ Death: When HP drops to 0 or lower, the investigator will 
  die at the end of the following round. During that time a 
  friend may intervene. See Healing section, p. 54 or in this 
  reference document.
  ๏ Acid: Note that this damage is only to be used in cases of 
  significant contact, such as the immersion of a hand or arm.
  • Weak Acid deals 1d3-1 damage per round.
  • Strong Acid deals 1d4 damage per round.
  • Very Strong Acid deal 1d6 damage per round.
  ๏ Drowning/Suffocation: If the investigator is unable to 
  breathe (due to water submersion paired with a failed 
  Swimming roll or a cloud of gas containing no oxygen), the 
  player may attempt a d100 roll of CON x10 or less for the 
  first combat round in order to hold his breath. In subsequent 
  rounds the multiplier drops by one to CON x9 in round 2, 
  CON x8 in round 3, etc. Surprised investigators may begin at 
  a lower multiplier. On a failure the investigator has ingested 
  something not breathable and takes 1d6 damage per round 
  until escape, rescue or death.
  ๏ Explosion: Damage is calculated based on the power and 
  radius (in yards) of the explosion. The explosion’s damage 
  reduces by 1d6 each two yards away from the center of the 
  blast. A stick of dynamite deals 5d6 damage at a range of 
  1-2 yards, 4d6 at 3-4 yards, 3d6 at 5-6 yards, etc. Larger 
  explosions get larger increments of damage. An Abrams 
  tank anti-personnel round deals 15d6 at the first four yards, 
  14d6 at 5-8 yards, etc. Roll damage separately for each target. 
  The Keeper is encouraged to change the range increments 
  and damage values to suit the type of explosive used.
  ๏ Fire: Burns of all kinds fall under this category. Damage 
  from this source can lower APP and CON scores as well as 
  current HP. 
  • A hand-held torch thrust at a target deals 1d6 damage 
  and the target makes a Luck Roll to prevent hair and 
  clothes from burning. If failed, the target continues to 
  take 1d6 damage per round without application of the 
  torch. Use a Luck or First-Aid roll to put out the fire, or 
  perhaps a Sanity roll to stifle panic.
  • A large bonfire deals 1d6+2 damage and engulfs the 
  target’s clothes and hair.
  • An average sized room in flames deals 1d6+2 damage 
  per round to each person trapped inside. A Luck Roll  
  is to be succeeded each round for each investigator in 
  order to prevent asphyxiation. If the roll is failed, begin 
  asphyxiation as per the drowning rules.
  • Larger fires are special cases to be described 
  individually. Just remember, the threat of death always 
  makes for good gaming.
  ๏ Poison: Poison strength is measured in potency (POT). 
  Higher numbers mean stronger poison. Use the Resistance 
  Table to roll POT vs. CON, with the POT as the attacker. If 
  the target fails, something bad happens, usually in damage 
  equal to POT. If the target is successful, perhaps half POT 
  is taken in damage or no damage at all. The Keeper is 
  encouraged to be creative with the effects of poison and use 
  the table as a guideline.
  HEALING
  ๏ Natural Healing: Investigator’s heal 1d3 HP per game week.
  ๏ First Aid and Medicine: A success with either skill 
  immediately restores 1d3 HP due to a single wound or injury. 
  Investigators healed with First Aid also receive the 1d3 HP 
  recovery at the end of one week. Investigators treated with 
  Medicine heal at a rate of 2d3 per week, including the first 
  week. Each treatment is specific to one injury. If Medicine is 
  not applied weekly, the rate drops back to the natural healing 
  rate. HP cannot be restored past the average of SIZ + CON.
  Call of Cthulhu
  Basic Role Playing System Combat Reference
  All references to the Basic Role Playing System, the game of Call of Cthulhu and other materials herein are Copyright Chaosium, Inc.
  
SOURCE: textdata/thevault/Call of Cthulhu (CoC) (BRP) [multi]/EXTRA/Resources/CoC - Combat Reference Sheet.pdf