Omen of Resurgence not doing it's job

My HCSSF char just died while i had the omen of resurgence on in my inventory, and my hp got under 35% before getting killed( i mean i did not get 1 shot). Before i got last hit i was at 31% HP.
Here is the death: https://youtu.be/IT2KE6J5tsw
Idk, back to the beach i guess.