PoE 3.19 added a new Notable Ascendancy Passive Skill to Juggernaut: Untiring.
Players can restore life by using flasks, gaining life regeneration from passive skills and equipment, or leeching life from enemies, among other mechanics. Life is fully restored upon entering a town. Light radius is based on current life.
It also grants life regeneration based on the amount of physical damage that was mitigated from hits.
The prevented damage is the difference between the calculated damage before mitigation and the damage taken after all steps of mitigation if that difference is positive, including not just physical damage reduction but also Block and Spell Suppression. If the user takes more damage than the amount calculated before mitigation, it will not count as “negative” prevented damage.
The keystone Divine Shield uses the same wording to regenerate energy shield instead.
Petrified Blood’s damage spread mechanics do not count as mitigation, and therefore do not contribute to “prevented damage”.
Unbreakable(wiki) is a Juggernaut Notable Ascendancy Passive Skill. It also grants 1.5% of Physical Damage prevented from Hits in the past 10 seconds is Regenerated as Life per second.
Divine Shield(wiki) is a keystone passive skill. It also grants 3% of Physical Damage prevented from Hits Recently is Regenerated as Energy Shield per second.