So, right now in ADOM, we have one kind of poison and one kind of sickness, with very specific effects on them. I was thinking that it might be nice to introduce a variety of different poisons/diseases that could afflict the character with different effects. Aside from adding variety, I think this might be also a nice balancing mechanism--basically it gives the opportunity to tune early game poison/sickness effects to be a little less devastating, and tune up late game poison/sickness to make them more relevant.

Here's a few ideas of what this might look like:

Poisons:
-Neurotoxin: Base energy cost of all actions is increased to 2000. Le, Dx, and Pe are reduced substantially. Spells fail unless a Wi check is passed. Does not deal damage.
-Hemotoxin: Greatly increased chance of Bleeding, Bleeding! etc. from all attacks, extra damage from bleeding. HP regeneration is stalled. Minor damage.
-Soporific: HP regeneration is increased dramatically; DV, to-hit, speed and to-damage are reduced dramatically. When poison wears off, PC falls asleep for a few turns.
-Hallucinogen: Gives temporary boost to Pe, Le. Directions are reversed. All monster skins and descriptions are replaced by those of a WMoPC.

Sickness:
-Leprosy: PC gains the equivalent of a 5 point "immune to pain" talent. HP and Max HP (and health bar) stats are obscured. Boosts Wi at expense of Pe, Dx, Ap, Ch. Wounds leave scars.
-Rabies: PC is locked in Berserk and will attack neutrals without prompting. Damage is increased, but to-hit is reduced dramatically. Most stats reduced while Rabid, and all stats except St are continuously abused.
-Kuru: Penalty to speed, Dx, Wi, Le, abuses Dx, Le. Base action cost increased slowly throughout the course of the disease. Can be brought on by cannibalism.
-Yellow fever: PC will not eat, even if starving. PC suffers periodic damage.

These are just ideas, of course. I've intentionally made it that not all of these effects are necessarily negative. I think one interesting thing might be to give, for example, Demon Daisy or Devil Rose some effect that has some situational use (eg. Soporific) rather than these herbs being otherwise useless.