Anosia

[Alitis]

It could be that the more wounds you get from specific things like snake or insect poisons, the more your immune system strengthens ( like a Quality curve ) and the lesser impact you have from them
The top cap would be anosia ( getting rid of the annoying midge bites at last, after years of playng probably )

[Oswald3]

idk anything about coding, so correct me if Im wrong, but this seems tough to do.

[Lunarius_Haberdash]

idk anything about coding, so correct me if Im wrong, but this seems tough to do.

Really not. A bit tricky to properly balance, perhaps, but not hard to code.