Figured out a formula.

[LaGlace]

theres a variety of poisons, the strongest one does 5%, but they all do some %. the spell puinsein, does 200.

[MeltDownZ]

and if you wernt newb you would know that their is a stronger poisin such as in fc now
noone can lure unless they geta newb rouge to poisin them in arena first
so that they cant get the stronger poisin casted on them

[LaGlace]

if i werent newb eh?  who am i? 
anyway, fc poison IS 5%, a second of course, as well as deep cr and chaos, not sure about deep andor, the dungeon poison is still weak. also, two new kinds of 'poison' called disease(cast in canals, does, we think, 1% a second) and rot(300 damage, or a percent, no idea really, lasts very short time)
not sure if either can be cast on a person who is already poisoned