Path of Exile Corrupted Soul has two modifiers that define its gameplay. The first is that 50% of non-chaos damage taken bypasses Energy Shield, while the second grants you 15% of Maximum Life as Extra Maximum Energy Shield. In this article, we will delve into the mechanics and interactions of Corrupted Soul, a Timeless Keystone passive skill. We'll explore its benefits, drawbacks and how you can effectively incorporate it into your builds.

• Acquiring Corrupted Soul
• Corrupted Soul Downside 
• Making the Downside an Upside
• Synergy with Ascendancy Notables
• Additional Energy Shield Recovery Options
• Stun Prevention
• Upside: Extra Maximum Energy Shield
• Replica Soul Tether and Energy Shield Scaling
• Combining Corrupted Soul with Other Keystones
• Eldritch Battery and Mind over Matter
• Other Defensive Options

↖ Acquiring Corrupted Soul

Corrupted Soul can be obtained by socketing a specific Timeless Jewel into your passive tree. These Jewels dominate passive skills within their radius, including keystones, which are transformed into new keystones based on the type of the Timeless Jewel. Corrupted Soul is always granted from the Glorious Vanity Timeless Jewel when its name is Doryani's Invitation. Additionally, you can acquire Corrupted Soul by using the Replica Soul Tether belt, which drops from Grand Heist blueprints for Replica and Experimented items, or by obtaining the unique shield, Marzota's Machination. Note that Marzota's Machination grants multiple keystones, complicating its usage.

↖ Corrupted Soul Downside 

Let's discuss the downside first. By default, chaos damage completely bypasses Energy Shield, while other damage types interact with your Energy Shield until it is depleted, after which the damage affects your Life pool. With Corrupted Soul, half of all non-chaos damage taken now bypasses your Energy Shield. This means that 50% of non-chaos damage goes directly to your Life, while the other 50% damages your Energy Shield first if you have any. 

↖ Making the Downside an Upside

Interestingly, Corrupted Soul's downside can actually be used as an upside for most builds. The reason is that builds utilizing Corrupted Soul typically have substantial Health pools, allowing them to benefit from the additional Energy Shield based on their Life. It is rare for a build using Corrupted Soul to have more Energy Shield than Life. By splitting the damage from non-chaos sources between your Life and Energy Shield, you do not lose any efficiency in terms of protection from your Energy Shield because it would still deplete fully before your Life reaches zero.

↖ Synergy with Ascendancy Notables

Corrupted Soul synergizes exceptionally well with the Inquisitor's Sanctuary and Pious Path ascendancy notables. Sanctuary provides consecrated ground and life regeneration while stationary, and Pious Path allows the consecrated ground to linger after moving, granting life regeneration that also recovers Energy Shield. This combination effectively increases your effective Health pool against non-chaos damage. Another synergy exists with the Divine Shield Keystone, located on the far left of the passive skill tree between Templar and Marauder. This Keystone prevents Energy Shield from recovering above the amount of your total armor and regenerates 3% of physical damage prevented from hits recently as Energy Shield per second. This pairs well with the Bone Shatter skill, which deals physical damage to the user and grants a trauma buff. Builds focusing on sustaining multiple trauma stacks can mitigate the self-physical damage and gain strong Energy Shield recovery through Divine Shield.

↖ Additional Energy Shield Recovery Options

Other notable energy Shield recovery options include the Occultist's Vile Bastion node, the Necromancer's Essence Glutton, and the Trickster's Soul Drinker tendency notable, which provides energy Shield leech when used with life leech or other forms of life recovery. The Trickster's Polymath notable offers incredible recovery for both resources while mapping. Additionally, if your build has decent evasion, you can make use of Ghost Dance, which recovers Energy Shield when hit. The Betrayal modifier found on body armor and belts is also worth considering, as it regenerates Energy Shield while a rare or unique enemy is nearby, making it useful during dangerous encounters such as mapping or boss fights.

↖ Stun Prevention

Corrupted Soul's damage splitting also provides an inherent 50% chance to ignore stuns when the damage is dealt to Energy Shield. Since you have Energy Shield active more often due to the damage split, stun prevention is active for a larger portion of the time. However, many builds aim for full stun immunity regardless of this effect.

↖ Upside: Extra Maximum Energy Shield

The major upside of Corrupted Soul is gaining 15% of your Maximum Life as extra Maximum Energy Shield. This modifier allows you to acquire a significant amount of Energy Shield on hybrid Life and Energy Shield builds. The gained Energy Shield is scaled by any increases to Maximum Energy Shield. For example, if you have 6,000 Maximum Life and 50% increased Maximum Energy Shield, allocating Corrupted Soul would grant you 900 Energy Shield, which would then be scaled to 1,350 Energy Shield.

↖ Replica Soul Tether and Energy Shield Scaling

The Replica Soul Tether belt grants additional Extra Maximum Energy Shield on top of the Corrupted Soul Keystone. This bonus scales with Catalysts, allowing you to reach a total of 22% of your Maximum Life as Extra Maximum Energy Shield from the belt slot alone when using a maximum roll Replica Soul Tether with 20% quality.

↖ Combining Corrupted Soul with Other Keystones

If you're using the Pathfinder class and a Replica Soul Tether to gain the Corrupted Soul Keystone, you can use your Timeless Jewel slot to acquire the Supreme Decadence Keystone, granted from an Elegant Hubris Timeless Jewel when its name is Kaedo's Revelation. Supreme Decadence applies life recovery from flasks to Energy Shield as well, combining well with the Master Surgeon notable to gain recovery for both Life and Energy Shield from your life flasks constantly. Be aware that both nodes impose a penalty on life recovery from flasks.

↖ Eldritch Battery and Mind over Matter

With Eldritch Battery and Mind over Matter, you can create a build where 40% of the damage taken to your Life is redirected to your Mana due to Mind over Matter, while your Mana is protected by Energy Shield through Eldritch Battery. Corrupted Soul then splits the non-chaos damage taken from Energy Shield, which would bypass it and attempt to damage Mana instead. In most cases, when Mana is fully reserved, the damage bypassing Energy Shield will be dealt to Life because you have no Mana. This combination reduces the effectiveness of Mind over Matter by half for builds that reserve most or all of their Mana. However, it can still be useful as long as your Energy Shield doesn't exceed 25% of your total Life.

↖ Other Defensive Options

If you have good Energy Shield recovery, consider using Frost Shield for additional defenses. It grants a boost to spell critical chance while also providing a nice defensive bonus. Additionally, various defensive options found on other Timeless Jewel keystones or the belt slot may compete with Corrupted Soul, offering different advantages and stats that can benefit your build.

Conclusion:

Corrupted Soul is a fantastic Keystone for increasing your effective Health pool when used correctly. While it may not be suitable for low-life builds that aim to scale Life and reserve it, most builds utilizing Corrupted Soul can benefit greatly from the additional Energy Shield it provides.