World Building 101: The Problem with Diseases

Diseases are a fact of life. Everyone gets sick from time to time, but with modern medicine and sanitation, epidemic diseases are thankfully fewer and less devastating than they were in ancient times. Still, disease is such a universal part of existence that its inclusion in a D&D campaign should go without saying, right? Maybe not so much as you might assume. The span of history that most D&D campaigns draw most heavily from may be full of plague and pestilence, but frankly, getting sick just isn’t much fun, and in a world with curative magics, it can be hard to make it stick on a player character.

At the time of this article’s writing, there are nearly twenty diseases for use in a campaign—though some more common than others. The effects range from bad to worse, and in general the ultimate result of being infected and proceeding down the disease tract to the final condition is that the player character will be removed from the game until such time as a cure disease ritual can be cast. Diseases-inflicting attacks are present on fewer than fifty creatures, a majority of which actually inflict one of four common diseases—filth fever, moon frenzy, chaos phage, or mummy rot—with other vectors of infection largely relying on DM fiat.

A character successfully hit by a disease-inducing attack is given a saving throw at the end of the combat to avoid becoming infected. Other vectors of infection—direct exposure or prolonged exposure—function as attack rolls against the target player. In almost all cases, the immediate effect is that the PC is penalized, from loss of healing surges or less effective healing to direct penalties to attacks or defenses. In effect, contracting a disease is punishing a player for a poor die roll by inflicting further long-term penalties, which is both arbitrary and unlikely to be something that the player appreciates. Given the long term risk of being removed from play if the disease is not treated, in most cases, getting rid of the disease will become a high priority for the player. Barring time-critical story reasons, it may become the highest priority for the entire party, since any of the characters operating below optimal efficiency could bring the group down as a whole.

The DCs to stabilize or improve are generally not too onerous at any given level—even if an infected character is not trained in endurance, chances are someone in the party will be trained in heal and able to get aid from other characters in trying to cure the afflicted companion, meaning that in general there’s a better than even chance of not worsening provided the character is aware of the disease. After sixth level, it’s not unreasonable to assume that any party faced with diseases on even a semi-regular basis will have picked up the Cure Disease ritual, rendering diseases to a minor inconvenience at best in most situations. The barrier becomes the amount of ritual components available to the party at a given time, and disease-happy DMs may find their players growing resentful after awhile. If there’s no pressing danger or time sensitive mission, it’s not unlikely that players will simply hole up and refuse to proceed until the infected player is cured, either by endurance and heal checks or by ritual magics.

What all of the above boils down to is that, while including sickness and disease in a campaign setting may be realistic and can definitely create effective story hooks, applying the diseases to the player characters themselves is less than desirable on a regular basis. This does not mean that diseases should be avoided, however—simply that they should be used sparingly and with due consideration.

As story elements, diseases come into their own. The above analysis of the relative ease of shaking off a given illness apply to heroic characters, but what of the common folk of a given city or village? A group of high level explorers laden with the treasure of a dozen adventures can easily afford to cast the Cure Disease ritual a few times, but when the village’s population of several hundred people (or a city with thousands of citizens) all fall ill with an epidemic, the cost quickly becomes prohibitive even to the wealthiest adventurers. Alternately, your players may be afflicted with a disease, but if the king’s daughter is to be sacrificed at midnight tomorrow and time is of the essence, then dealing with the cure may have to take a back seat to rescuing the girl. This kind of situation is a good way to shift the player’s priorities, but be aware of the penalties the disease inflicts when designing the encounters the players will face while under its effects.

When you do apply diseases, be it on a PC or an NPC, it’s important to be descriptive. What are the physical symptoms, and how do they manifest themselves? How do people react to a character who is visibly ill—with guarded wariness, or outright hostility, or even fear? What does the disease feel like—beyond the mechanical effects, is there a strange aftertaste or unpleasant odor in the infected? Remember too that fantastic diseases should have fantastic symptoms, so be creative when inventing and describing sicknesses for your game.

The disease track can be used for other things, as well—a recent Dungeon article used it to represent magical curses. Instead of endurance checks, specific things may trigger the progression of a curse—time, perhaps, or violations of specific conditions. This could be used to represent a geas placed on a character, as well, with the curse worsening each time the character violates a given taboo and alleviating only when the character has made amends or atonement via a specifically defined method. Removing the curse or geas entirely may require the completion of a quest—this idea places control of the progression much more in the hands of the players, and acts as a very good story hook along the way.

Ultimately, diseases, curses, and the like can add a lot to a game, but they must be handled with a great deal of care when applied to players in order to ensure that everyone still has fun. They can bring in a number of interesting story options and add a degree of realism to the setting, provided they are given the appropriate amount of caution and awareness on the part of the DM—otherwise they become merely an irritant and a slight road bump, rather than a dramatic or interesting part of a campaign world.

Comments (5)

Spiralbound (October 8th, 2010)

Rather than using GM fiat or PC-only rules to shield PCs from disease, there is another option. Simply design diseases such that once PCs are mid to high level they are too hearty and hale to easily contract most illnesses. After all, PCs are intended to represent the above-average heroic personalities of fantasy. If, for example a given disease required a Fort save of 12 or 15 to resist, it would become easy to avoid once a PCs Fort was above +5.

mike (October 9th, 2010)

make diseases that only be cured by casters of a certain level or have spells like cure disease III that are needed for really bad diseases.

Also, cure disease spells don’t confer immunity to new attacks or could make you more susceptible to re-infection. Only letting the disease run its full course wold let you be in the clear.

Gestalt Gamer (Dan) (October 9th, 2010)

I agree, I have had a lot of difficulty implementing diseases versus PCs though I do like to use them as plot points in games. In the game I am running right now I stole an idea from Warcraft 3 and blighted a towns food supply with a necromantic disease. In this next session the party will find the interior of the besieged city filled with newly formed zombies who will try to do the work of the invading army for them.

Brandan Landgraff (October 10th, 2010)

Actually when I wrote this article several weeks ago I had just begun a story arc in my campaign in which several infiltrators from a nation the party basically helped defeat in a recent war have got into the capital city of the PC’s home nation and managed to taint several of the wells with plague. I don’t intend to do the WC3 plague bit, it’s more to create panic and chaos as a backdrop for some really big events coming up at the capstone of the heroic tier, but I can definitely say Warcraft was on my mind in terms of how diseases have been handled previously in similar settings.

C.W. Bush (October 10th, 2010)

I think diseases can be a fantastic plot tool. I spent three sessions once establishing the party’s place in a quaint little village - forging friendships, finding local drinking haunts etc.

Then having a disease slowly kill off townspeople meant that the party had an extra incentive to act. It also drew their attention away from signs of impending attack as they rushed around tending to the ill and looking for a cure.

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