Dire Diseases (5e Variant Rule)
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These rules are intended to make Curses and Diseases more dire.
All diseases and curses should be divided into "lesser", "greater", "incurable", and "soul bound".
Curing Diseases and Curses
Spells or effects that say they cure 1 disease now "cure 1 lesser disease". Spells that say they cure all diseases now "cure all lesser diseases or cure 1 greater disease". (The same rules apply to curses, except that the word disease should be replaced with cure).
No spell or effect in the game should be able to cure "incurable" or "soul bound" diseases and curses. Each should have their own special cure either stated in the description of set disease or curse, or made by the DM.
Incurable diseases and curses leave afflicted creatures upon death.
Soul bound diseases and curses stay with the afflicted forever, even if they die and come back with only very special ways of curing it. Some of them might even be incurable even by wish if the DM wills it.
How They Work
Most diseases are one greater sickness which is linked to, and causes a number of lesser sicknesses to effect the host. (Note incurable and soul bound can be greater or even lesser sickness which are just harder to cure).
Example of effects form a a sickness in normal 5e "Sewer Plague" The infected creature suffers one level of exhaustion, and it regains only half the normal number of hit points from spending Hit Dice and no Hit Points from finishing a long rest. At the end of each long rest, an infected creature must make a DC 11 Constitution saving throw. On a failed save, the character gains one level of exhaustion. On a successful save, the character’s exhaustion level decreases by one level. If a successful saving throw reduces the infected creature’s level of exhaustion below 1, the creature recovers from the disease.
and this is how it would look in this system.
Greater Sickness "Sewer Plague". The next rest after catching this sickness Sewer Plague infects the host with the lesser sicknesses: "Exhaustion" "Exhausting Sleep" "halved healing" and "Not recovering hitdice"
"Sewer Plague" dose not cause any of these effects to stack however when one or more is removed each day it will re-infect the host with ONE of the effects that was cured. (this means if all the lesser sicknesses are cured but the greater sickness remains the host will day by day regain all the lesser Sicknesses one at a time.
(NOTE A greater sickness may never be cured until after all the lesser sickness linked to it are also cured.)
The lesser Sicknesses form this example.
Lesser sickness. "Exhaustion" Causes the host to take on 1 level of exhaustion when they get this sickness.
Lesser sickness "Exhausting Sleep" At the end of each Long Rest, an infected creature must make a DC 11(feel free to change the dc's dms) Constitution saving throw. On a failed save, the character gains one level of Exhaustion. On a successful save, the character’s Exhaustion level decreases by one level(NOTE can only remove exhaustion levels caused by this sicknesses)
Lesser Sickness "halved healing" When this creature would be healed the amount they heal is cut in half
Lesser sickness "Not recovering hitdice" the host dose not recover hit dice.
As you can see a Greater Sickness in of it self dose not cause negative effects instead each effect is separated and made in to there own lesser sickness.
Most Greater sicknesses will infect the host with all the lesser sicknesses and replace them when a lesser sickness is cured. The rate at witch this happens is based on how fast acting the sickness is.
A Very slow Sickness will one by one effect the host with it's lesser effects once every X number of weeks or months. (maybe a d4 or 12 weeks or months) I would suggest making Sicknesses this slow incurable and or have very powerful lesser sicknesses)
A Slow sickness will infect the host with one of its lesser sicknesses once every X days. (I suggest a d4 or d12 days)
A normal Sickness Will infect a host with between 2-4 of its lesser sicknesses after the first long rest. Then each day it will either add another lesser sickness or replace 1 of the lesser sicknesses each day.
A Fast Sickness Will infect the host with all of its lesser sicknesses the rest after getting it then replace 2 cured sicknesses each day.
A Deadly Fast Sickness Will infect a host with one of its lesser sicknesses every hour and replace them at the same rate. (feel free to make it every 2 hours or 4 or a d4)