i have an idea it goes this way...
that shield reduces 2 damage(upped)
lets say you take 10 damage.
why not the poison counter turns into 4 instead?because you take the damage every turn.
if you would compare it to a normal shield e.g. diamond shield
10 damage-3=7
while this shield
10 damage-2=8 right?then divide it by 2.
so every turn you take the poison damage.
example:
your opponent deals 10 damage every turn
lets say a 6/5 pegaus(dive)
1st turn
12-2=10/2= 5 poison counter
100hp-5=95
2nd turn
12-2=10/2= 5 poison counter
95hp-10=85
3rd turn
12-2=10/2= 5 poison counter again
85hp-15=70 hp.
30 damage w/in 3 turns
while
(diamond shield)
turn 1
12-3=9
91 hp left
turn 2
12-3=9
82 hp left
turn 3
12-3=9
73 hp left
thats only 3 damage but the poison counter gets stronger everytime right? *cough* *purify* *cough* so this way you can stall and necrosis>diamond shield
and there is a chance of killing your opponent first because you take damage after your turn.this shield can be usefull for fg farming also.