First, the skill challenge concept from Dausuul... very interesting! I might have to use that wholesale or at least mess with the concept.
Second, poisons are effectively at-will powers that cost money, so they can't (for game balance reasons) be that powerful. Basically, one standard action (to apply the poison) gives you a free secondary attack. In other words, one standard action gives you an attack. Given that the poisons pretty much all have special effects (most of which are found in the equivalent of encounter or daily powers), I think they're pretty well balanced.
That said, I can certainly see from a "real-world" perspective how you might want poisons to last longer. My first instinct says you could create poisons that instead of (save ends) state (3 saves end) or (save reduces damage by 5; when damage is reduced to 0, all other effects end). For things like drugs or long-term poisons you could have:
5 damage each hour (save ends, save after first exposure and each hour thereafter)
Though I think it would be more interesting to have effects like:
Cannot spend a healing surge or cannot spend more than one healing surge per day.
I think the mechanic presented is limited, but easily extensible.
Second, poisons are effectively at-will powers that cost money, so they can't (for game balance reasons) be that powerful. Basically, one standard action (to apply the poison) gives you a free secondary attack. In other words, one standard action gives you an attack. Given that the poisons pretty much all have special effects (most of which are found in the equivalent of encounter or daily powers), I think they're pretty well balanced.
That said, I can certainly see from a "real-world" perspective how you might want poisons to last longer. My first instinct says you could create poisons that instead of (save ends) state (3 saves end) or (save reduces damage by 5; when damage is reduced to 0, all other effects end). For things like drugs or long-term poisons you could have:
5 damage each hour (save ends, save after first exposure and each hour thereafter)
Though I think it would be more interesting to have effects like:
Cannot spend a healing surge or cannot spend more than one healing surge per day.
I think the mechanic presented is limited, but easily extensible.