The T3 Avernus hunt item "Bone Devil Ribcage" does not increase the player's Critical Chance and Critical Severity when healing, as stated in the tooltip.
Tested with warlock healer.
Viperion - DragonTribe guild leader.
Playing Healers (Cleric, Bard & Paladin) and DPS (Warlock & Wizard).
It does not have an icon that shows its activation.
If it's matter of being unable to proc the bonus ... has anyone tried the silly meme strategy of pairing the Barbed Cultist Greaves (reduces your HP by 20%, or "your max HP count times 0.8x") with any of the "% of HP" proc gears?