How is that garbage? There may be better, depending on what you're looking for, but this is definitely good. There are only 5 PDT/DT rings to choose from (Non-augmented), 2 being stupid annoying to get, and 2 being only 1-2 pdt.
I would take this ring any day.
cause on a physical hit, the -20 hp actually hurts you more than you gain from the 4% dmg reduction up to a 500 dmg hit where they are equal. ontop of the enmity lost when taking dmg is a function of the amount of dmg you take vs your total HP, which this ring reduces.
Would only really use when i knew i would be taking monsterous amounts of physcial dmg to cap out my -pdt, but probably would stick with +hp instead.