If you have Negative Resistance Potion Efect (ex. Resistance Level -5)
Poision Effect can kill you instead of that you health is half heart
How to do it
1. give you a Negative Resistance Potion

/give <name> minecraft:potion 1 16384 {CustomPotionEffects:[0:{Id:11,Duration:10000,Amplifier:-6}]}

2.1. give you a Poison Potion

/give <name> minecraft:potion 1 16384 {CustomPotionEffects:[0:{Id:19,Duration:10000,Amplifier:0}]}

3.Throw both potion on you (make sure that your hunger are always full )
4.wait and see that you are killed by poison

I think that Negative Resistance amplifying damage is intended
but it should not make the poison kill you