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
Negative resistance levels are not supported, and the fact that they would cause more damage seems intended.