So... this is a necro topic atm, but I've been playing around with the variant of this card implemented under openEtG.
It was implemented so that it basically just upgrades an already existing poison status to neurotoxin status but has no effect if the victim is unpoisoned or already has neurotoxin.
It is definitely interesting, but it practically forces a duo to make it really worthwhile...
I definitely like the requirement of a prexisting poison status, but I think it is a little too limiting.
I think it would be cool to work it as:
-If victim is unpoisoned, add 1 poison
-If victim is poisoned but lacks neurotoxin status, upgrade them to neurotoxin status
-If victim already has neurotoxin status, add +1 to their poison level
You could word it as:
"Add neurotoxin status to a poisoned opponent. Or inflict 1 poison if they already have neruotoxin or are unpoisoned"
That way, this card becomes useful in its own right without needing other poison sources, but still leaves the poison card itself effective.