I really like the idea of having a ton of different poisons throughout the game that each have different affect, as Jason was mentioning. Putting antidotes for each poison, and placing them throughout the mud, makes for a fun game of figuring out the right poison for the right person, which poison you will be attacked with and preparing yourself with the right antidote, and knowing where to find each poison/antidote. I suggest the antidote not be in the same zone as its corresponding poison. Placing the poison and antidotes in obscure areas will encourage exploring. Making them quest rewards will encourage questing. We could even make the level of difficulty of the quest determine the strength of the poison.
Can we add a tinker-like feature to poisons? Makes the timer shorter but the affects stronger.