
Upgrading your health is arguably the single most important thing for your survival in Doom: The Dark Ages.
To make it through all the challenges entailed by fighting demons with minimal suffering, improving your health could mean the difference between life and death. And you can considerably improve your chance of staying alive if you upgrade your health in Doom: The Dark Ages.
But your health bar is not a simple task. First, you need to prove yourself by fighting stronger – and quite annoying – demons and sucking their essence to make you stronger.
In this in-progress Doom: The Dark Ages guide, we explain how to upgrade your health plus show you where to find all health upgrades we’ve found so far.
How to upgrade health in Doom: The Dark Ages

While your guns, shield, and melee attacks can be upgraded using special currencies to buy new abilities in a Sentinel Shrine, increasing your health requires a little more fighting.
Following the same idea as upgrading your ammo capacity and armor, health upgrades are permanent and obtained when you defeat leaders that grant those upgrades. All you need to do is to defeat them to collect their Demonic Essence.
Leaders are stronger than your usual demons. You can identify them with ease, since they have a blue-hued plus sign floating above their head.
Below, see maps showing the locations of all health upgrades we’ve found so far in Doom: The Dark Ages and the requisite leaders they’re associated with.
Hebeth

You face the first leader in the Doom: The Dark Ages in the second level, Hebeth. You find the leader of this level in the final segment of the map. Before you can challenge them, you must clear all the waves of enemies with all kinds of demons you found until then.

A short cutscene will play when you’re done, showing the leader. They are a stronger version of the Pinky Rider demon. They still shoot a Hell Surge projectile to attack you, but their special move is a wave of shields. One of the shields is green and you must try to parry it.
If you pay attention, the beast has armor. Even though it protects them from your attacks, the armor follows the rule as the regular metal shields some enemies carry. Superheat the armor then use the Shield Throw to remove it completely.

Since this is a tough enemy, consider keeping some of the other demons alive during the fight so you can follow one of our tips and kill them to recover life.
Check back soon for more health upgrades!
Source:https://www.polygon.com/doom-dark-ages-guides/599061/health-upgrade-leader-locations-all-where-to-find