Here are some things to know:
Before this code change, the EXP that a mob distributed when it died to each player as based on the portion of damage that player did compared to the total damage that the mob received from all sources.
This meant that if a mob with 600 exp, took 1000 damage from poison, and 1000 damage from walking in to a trap, and you did 8000 damage to it too, and it died.
You would receive (8000/(1000+1000+8000)) * 600 = 500 Exp
Now in this new system, because exp is split evenly between everything that deals damage to a mob, including poison, traps, and charmies.
This means that if this same mob with 600 exp, took 1000 damage from poison, and 1000 damage from walking in to a trap, and you did 8000 damage to it too, and it died.
You would receive (600/3) = 200 Exp
But it also means that you gain an even portion of exp from your group, for doing any amount of damage to a mob.
I have taken some suggestions from players that poison does very low amounts of damage in proportion to the exp it takes.
There are two solutions to this:
Either change the way poison damage works, so that it counts as damage done by a player. (I don't like this idea personally because it is easy to abuse, just run in a place with lots of mobs, and poison them all, and flee or retreat)
Or
Increase the amount of damage poison does, to make it worth the exp you invest in using it.