I don’t think I’ve ever been 100% satisfied with diseases in role playing games, not even with the rules in Blood & Treasure. This post is an attempt to create a system a bit more granular than most. In this system, diseases are not named, but rather are collections of random symptoms, with the number of symptoms and their severity based on the general severity of the disease.
THE BASICS
When struck with a disease, say from the bite of a rat, a prolonged stay in sewers (or a flophouse) or a biological trap, an adventurer must pass a Fortitude saving throw to avoid suffering any ill effects at all. This might represent a case where the contagion is simply not introduced to the character’s system, or it is introduced and the character’s immune system neutralizes it very quickly.
If this Fortitude save fails, the character is infected. First, we need to know the severity of the disease. The Treasure Keeper can either roll dice to determine severity, or base it on the hit dice of the monster that spread it or the level of the dungeon on which it was acquired.
D% (HD or LEVEL): SEVERITY (SYMPTOMS)
01-75 (0-4 HD): Minor Disease (1d3 minor symptoms)
76-90 (5-9 HD): Medium Disease (1d4 minor symptoms, 1d2-1 major symptoms)
91-100 (10+ HD): Major Disease (1d4 minor symptoms, 1d3 major symptoms)
Symptoms begin appearing within 1d4 days.
The Treasure Keeper should now roll 1d4 minus the sufferer’s Constitution bonus. This is the number of days before the sufferer’s immune system has a chance of defeating the disease. It is possible that the disease can be fought off before any symptoms begin to appear.
Each day, a victim of disease can roll a Fortitude saving throw to attempt to throw off one symptom, usually the most severe, but in any event a symptom of the player’s choice. If the player is successful, that symptom is removed.
If the diseased character is active (i.e. not getting plenty of rest), they suffer a -2 penalty on this save.
All characters that spend time around the diseased character have a percentage chance each day to be exposed to disease. This percentage chance is based on the number of type of symptoms, with a 10% chance per minor symptom and a 5% chance per major symptom. Naturally, the non-diseased character is permitted a Fortitude save to avoid actually contracting the disease.
Note: If you want to give a more supernatural feel to diseases, you can rule that any adventurer who dies from a disease and is not burned or buried in consecrated ground rises as an undead with Hit Dice roughly equal to the number of levels they had in life.
MINOR SYMPTOMS (ROLL 3d6)
3. Exhaustion4. Fever, severe
5. Rash, major
6. Dementia
7. Rash, minor
8. Aches
9. Cough
10. Diarrhea
11. Fatigue
12. Fever, low-grade
13. Sickened
14. Stuffy head/runny nose/sneeze
15. Swollen joints, minor
16. Shooting pains
17. Spasms
18. Swollen joints, major
Aches
The character is possessed of aches in the muscles and joints and suffers a -1 penalty to attacks, Armor Class and Reflex saving throws (including task checks).
Cough
Roll 1d4 for severity; this is the chance on 1d6 per hour that your coughing attracts a wandering monster. After any major exertion (running, fighting, climbing more than 10 feet) you are fatigued until resting 10 minutes.
Dementia
The character is unsteady on his feet. When moving at more than half speed or fighting, he must pass a Reflex save each round to avoid falling prone for 1d4 points of damage. Whenever he is forced to concentrate on spell casting, he must pass a Will save to successfully cast the spell. The character suffers a -1 penalty on all Reflex and Will saves (including task checks).
Diarrhea
Not for the faint of heart. You suffer intestinal distress every 1d6 x 10 minutes and need to find a private place to deal with the problem. If you are not drinking a double ration of water, you suffer 1 point of Constitution damage per day due to dehydration.
Exhaustion
An exhausted character moves at one-quarter normal speed, suffers a -1 penalty to saving throws and task checks and her foes enjoy two tactical advantages against her in combat.
Fatigue
Per the normal rules for this condition in Blood & Treasure.
Fever, Low-grade
The character has a low-grade fever and suffers a -1 penalty to Will saving throws (including task checks). He also requires twice the normal daily ration of water. Failure to hydrate properly results in 1 point of Constitution damage each day.
Fever, Severe
The character has a severe fever and suffers a -3 penalty to Will saving throws (including task checks). He requires twice the normal daily ration of water. Failure to hydrate properly results in 1 point of Constitution damage each day. Finally, the fever causes hallucinations. Each hour, the character must pass a Will save or be struck with the equivalent of the confusion spell for 1d6 x 10 minutes.
Rash, Minor
The character suffers from a minor rash over a small portion of her body and suffers a -1 penalty to attacks, Armor Class and Reflex saving throws (including task checks) due to the discomfort. Each day, the character must pass a Fortitude save to avoid scratching and turning the minor rash into a major rash.
Rash, Major
The character suffers from a major rash over a large portion of her body and suffers a -2 penalty to attacks, Armor Class, Reflex saving throws (including task checks) due to the discomfort and a -2 penalty to Charisma-related task checks due to the physical marring. Each day, the character must pass a Fortitude save to avoid scratching and suffering 1 point of Charisma drain for permanent scarring.
Shooting Pains
The character suffers fierce, shooting pains. She suffers a -2 penalty to attacks, Armor Class and Reflex saving throws (including task checks). Whenever she is forced to concentrate on spell casting, she must pass a Will save to successfully cast the spell. The character suffers a -1 penalty on all Reflex and Will saves (including task checks).
Sickened
Per the normal rules for this condition in Blood & Treasure.
Spasms
The character suffers random severe muscle spasms. This translates as a tactical advantage for his foes in combat, a -1 penalty to Reflex saving throws (including task checks) and a requirement to pass a Reflex save each time he is walking on a precarious surface to avoid falling.
Stuffy Head/Runny Nose/Sneeze
You suffer a 1 in 6 chance per hour that your sniffling and nose blowing attracts a wandering monster. Any exposure to copious amounts of dust, pollen, molds and the like force you to pass a Fortitude saving throw or begin a sneezing fit that last 1d4 minutes, delaying the party and attracting a wandering monster on a roll of 1-2 on 1d6.
Swollen Joints, Minor
Minor swelling in the joints reduces movement by 5, grants the sufferer’s foes a tactical advantage in combat and imposes a -1 penalty to Reflex saves (including task checks).
Swollen Joints, Major
Major swelling in the joints reduces movement by 10, grants the sufferer’s foes a tactical advantage in combat and imposes a -3 penalty to Reflex saves (including task checks).
MAJOR SYMPTOMS (Roll 1d6)
1. Blood poisoning
2. Coma
3. Immune system attacked
4. Internal bleeding
5. Muscle damage
6. Nerve damage
Blood Poisoning
The disease is attacking the character’s blood. Each day the character must pass a Fortitude saving throw or suffer 1d6 points of Constitution damage. At 0 Constitution, the character dies.
Coma
The character falls into a deep, comatose slumber. While in a coma, she heals ability score damage at twice the normal rate and enjoys a +1 bonus to save vs. the other symptoms of her disease. After three days, the comatose character can begin making daily Will saving throws to come out of the coma. If three of these Will saves are failed, the coma becomes a permanent condition and can only be removed with a restoration, miracle or wish spell.
Immune System Attacked
The disease attacks the characters immune system, imposing a -2 penalty to all saves vs. disease (including saves against symptoms of disease).
Internal Bleeding
The character is bleeding internally, suffering 1d6 points of hit point damage and 1d6 points of Constitution damage each day that a Fortitude saving throw is failed. At 0 Constitution, the character dies.
Muscle Damage
Each day the character must pass a Fortitude saving throw or suffer 1d6 points of Strength damage. If the character reaches 0 points of Strength, she is paralyzed and dies in 1d6 hours.
Nerve Damage
Each day the character must pass a Fortitude saving throw or suffer 1d6 points of Dexterity damage. If the character is reduced to 0 Dexterity, he is paralyzed and dies in 1d6 hours.
NEW SPELLS
This disease system suggests a few new spells:
SUPPRESS SYMPTOM
Level: Cleric 1, Druid 1, Ranger 1
Range: Touch
Duration: 24 hours
This spell suppresses a single symptom of a disease for 24 hours.
CURE SYMPTOM
Level: Cleric 2, Druid 2, Ranger 2
Range: Touch
Duration: Instantaneous
This spell completely removes one symptom from a diseased character.
VIRULENCE
Level: Cleric 2, Druid 2
Range: Close
Duration: 24 hours
This spell makes all diseases within close range more virulent for 24 hours. All who suffer from these diseases suffer a -1 penalty on all saving throws against the disease, and the chance of exposure to the disease for others is doubled.
Land of Nod 