maybe the bitten creatures should get a poison counter
It does. I was following the wording from cards like parasite and toadfish. Those cards read "inflict 1 damage per turn" rather than specifically stating that they add a poison counter
There are plenty of spreaded disease ideas inside element, so I don't view this as a truly original idea. A rabid bat however is a good thought but I think it makes more sense if Rabies was an active ability with a activating cost or something.
I don't see anything in crucible or forge that randomly spreads poison or disease from one creature to another.
The closest I see are:
-In forge, there is Death adder that is like a neurotoxin version of parasite.
-In crucible Noxious bug adds poison on sacrifice based on attack
-Cholera spams -1|-1 to enemies based on stack size (crucible)
-Sludge has attack power based on poison level and the infest ability (armory)
...Unless I'm missing something I don't see any wandering / spreading plague ideas in any of the CIA levels past smithy.
Currently, poison has plague (which hits only enemies) and virus (which is a sacrifice based poison deliver)
I wanted a card which would be a powerful poison spreader but also included a double edge effect... there are a few that include poison and double edge effect (poison needle and a weapon that poisons wielder) but none of them have a mechanism that makes the afflicted spread the debuff to others.
If you can find some examples of spreaded plague ideas in circulation right now, it would help me to refine the idea a little more to make it unique.