currently that rune works like that: when u activate the mantra it puts a shield on u that absorbs 15% of ur total health.
how did it work before ? i havent paid attention to that mantra or rune.
now about the current rune
considering that on hell u have about 20-25k hp. lets say u have 25k hp, then the absorb amount is 3700. thats low for hell isnt it ? this rune is basically a waste of a choice cuz it does nothing. any other rune is better.