For this conversation, I think it might be helpful to provide some information on the intended design of Endurance. Endurance does apply to “oneshot” damage - any damage dealt to health below endurance threshold does get reduced by endurance amount - even if the instance of the hit happened while above endurance threshold. eg. IF you have 800/1000 health, threshold at 400 health take a hit for 500, 100 damage of that hit would be mitigated by endurance. This doesn’t prevent “oneshots” if the damage is high enough, which is intentional - it’s not meant to be a health gate.
Endurance is designed as a defensive mechanism which allows builds to have more time “on the edge” of death, where the most excitement is, fighting to hold on. To achieve this, the lower part of your life total gets this additional damage mitigation, allowing players to see and experience that low-life, holding on to the last string, but actually have more of a hold than it feels like in the heat of the moment. There’s also several mechanics that can make use of this by intentionally placing themselves within this threshold, such as liches, and Primalists. Endurance wasn’t meant to be viewed as “total average EPH calculated on a planner”, but rather its design is in the moment to moment combat feel.
I don’t say this to steer conversation, just to add context to the current design.