This gem increases healing received by the character from all sources with each successful hit they land, stacking 10 times and refreshing duration with each stack. Upgrading increases the healing bonus.
"Some say this stone derives its power from its owners life force, which is shortened with each use. Well I say any fight I can walk away from is a victory, and tomorrow can take care of itself." — Famed warrior Lenalas, the day before his death
Prior to 2.4.2, this gem instead reduced all damage taken by the character while under one or more hard Crowd Control effects by 30% (+0.4% per Rank), regardless of how many of them. Damage of the initial attack that applied the Crowd Control would also be reduced. Upgrading increased the damage reduction, which (technically) had a cap of 80% at rank 125.
At rank 25, it also healed the character whenever a Crowd Control effect was applied to them. Note that this healing occured after the damage of the attack that would have applied the effect was resolved, if any.
This gem only worked with the following effects: Immobilize, Freeze, Fear, Stun, Blind. Knockback and Slow would not trigger healing, and would not grant damage reduction for the duration, while Hex, Confusion, Taunt and Charm normally do not affect players. If the character was immune to the specific Crowd Control effect for whatever reason, the gem would have no effect.
It used to be one of the few gems with actual ranking limit, effectively becoming fully upgraded after rank 125.