There are 3 things in regard to poison that i have to say.
1. I really like the toxic laser challenge, i wish i could get the unique item that allows the laser to destroy hedges outside the challenge.
2.What if the poison item was buffed?
For example, after picking it up the first time, every additional time its picked up, not only does the damage gets increased, but also the duration of the poison gets increased a little bit?
Maybe even make it that the poison item increases the damage and the duration for the bloodgrass item?
3. What if the plant disease item would cause the poison effect to spread among nearby enemies, like the ricochet item, but only for the poison effect?