Cast on Critical Soulrend of Reaping
Perfect Agony Assassin Build

Updated for Patch 3.25

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Cast on Critical builds will use an Attack to Trigger a Spell, which is their main damaging component. This build uses Lancing Steel of Spraying Attack to Trigger Soulrend of Reaping Spell. More often than not you can see players leaning towards Attacks that have high Attack Frequency built into the Gem, and while Cyclone may be a good example of such Skill, you have to keep in mind that Lancing Steel of Spraying has the advantage of being a Ranged Attack which keeps your character much safer. It fires multiple Projectiles per swing so the Trigger Rate remains high. Soulrend of Reaping is a bare-boned Chaos Projectile Spell, but it does have high Damage and Crit Chance - one of the highest you get without any drawbacks or strings attached. It's improved with Piercing Shots and will cause enemies to explode on Kill thanks to Asenath's Gentle Touch Gloves so you don't need to worry about Clear Speed, which is usually poor for this Spell in particular. Soulrend will inflict Poison, the damage type we will focus on.

CoC builds rarely specialized in DoT because Critical Strikes and Damage over Time do not mix well. After all, Crit Damage does not improve Ailmet Damage, at least not in any significant way. This can be changed with the Perfect Agony Keystone which received a major buff in patch 3.25. It now translates the Critical Strike Multiplier into the Damage over Time Multiplier, while making the DoT Multiplier completely useless. It's much easier to gain a meaningful amount of Crit Multiplier, especially when compared to DoT Multiplier which is scarce and you get much less of it no matter the source. This archetype suits Assassin the most thanks to the Toxic Delivery which grants Poison Damage and Crit Chance. Noxious Strike, Opportunistic, and Unstable Infusion from the Assassin's arsenal are all excellent additions to this build. Capping your Crit Chance and Poison Chance at 100% should now be much easier.

It's not a durable build but we can still try to play the cards we've dealt ourselves. The CoC builds all have a high Hit Rate so the primary defensive layer will be instant Life Recovery on Hit. It nearly guarantees that you will stay on Full Life as long as you are Attacking. Just don't get Stunned or Frozen. It protects you from DoTs too. Besides that, the build has a somewhat high Maximum Life with Energy Shield recovered via Ghost Dance, capped Spell Suppression, and a high Evasion Rating. You're immune to Reflected Damage and enemies you Poison won't deal Critical Strikes. Also, you take 20% less damage if there are two big enemies near you, so the build is pretty safe in crowded areas or against specific bosses.

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1. Gameplay

Spray enemies with Lancing Steel and Soulrend Triggered with it. It's effective against packs of enemies as your Projectiles are very fast and they detonate foes on kill. To move around use Shield Charge. Against bosses deploy Arcanist Brand that will Curse them with 3 Hexes. Assassin's Mark is triggered automatically, and so is Temporal Chains, Immortal Call, and Blood Rage. Your Mana-Reserving Skills are Malevolence, Grace, and Arctic Armour.

2. Build's PROS & CONS

3. Leveling tips

Start with something that's not Cast-on-Critical and does not use Perfect Agony - capping Crit Chance is not an easy feat. We recommend following the Poison Blade Vortex Assassin build guide. You will start as a regular Poison build with Noxious Strike and Toxic Delivery - these passives are good even if your Crit Chance is low, and grow stronger the higher your Crit Chance is. There's still a lot to do even after you reach a high enough Crit Chance to benefit from Perfect Agony, so if you don't have gear ready to equip, play as the Blade Vortex and switch after acquiring it. This CoC build is complex and can't be easily assembled with no prior thought. Put your character into PoB and check the Attack/Cast Rate in "Calcs". Your Attack Speed has to be as close to the Trigger Rate Cap,and keep mind that if your Projectiles Return, they will hit twice after a delay.

Bandits:

Two Additional Passive Skill Points seem like the best option for this build

4. Final Skill Tree, Ascendancy Points, and Pantheon

Final Skill Tree:

97 Points Final Skill Tree (doesn't include Cluster or Unique Jewels)
123 Points Path of Building (PoB) link

Ascendancy points:

Preferably in that order:

1. Noxious Strike
2. Toxic Delivery
3. Unstable Infusion
4. Opportunistic

Pantheon:

Major God: Soul of the Brine King: You cannot be Stunned if you've been Stunned or Blocked a Stunning Hit in the past 2 seconds

Minor God: Soul of Garukhan: 60% reduced Effect of Shock on you

5. Final Gems links

[DPS] Lancing Steel CoC setup
	Lancing Steel of Spraying - The Attack which Triggers linked Spell. It Hits many times per swing and is ranged, making it one of the best Attacks for this purpose.
	Soulrend of Reaping - An extremely powerful Chaos Spell with unusually high damage and Crit Chance. It's the main damaging ability that will inflict Poison on Hit.
	Cast on Critical Strike Support - It allows Lacing Steel to Trigger Soulrend. Try to get the awakened version for a lower Cooldown, thus a higher Trigger Rate. With the awakened version you won't need any more Cooldown Recovery Rate to reach 7.58 casts per second.
	Void Manipulation Support - More Chaos Damage, which is the Poison's type of damage.
	Increased Critical Strike Support - Increases Crit Chance for linked Skills. You absolutely need a 100% Critical Strike Chance.
	Returning Projectiles Support - All Projectiles Return to you after Piercing, applying poison, and Triggering the Spell again. This way they can Trigger Soulrend on their way back, but the limit of CDR is still keeping you from triggering it too often - it only makes your projectiles stay longer to hit an enemy.

[UTILITY] Reservation setup
	Malevolence - More Damage over Time and increased Skill Effect Duration.
	Grace - More and increased Evasion Rating.
	Arctic Armour - While Stationary, you take less Fire and Physical Damage. It also grants Freeze immunity. You're Stationary when attacking and after taking a big Hit that Stuns you so it's reliable.
	Enlighten Support - Linked Skills Reserve less Mana.

[UTILITY] Curse setup
	Arcanist Brand - A Brand that Triggers all linked Spells once attached to an enemy. Use it against bosses.
	Despair - A Curse that lowers Chaos Resistance.
	Enfeeble - Reduces Accuracy Rating and causes enemies to deal less damage.
	Punishment - Enemies that are on Low Life take vastly increased damage.

[MOBILITY] Assassin's Mark setup
	Assassin's Mark - Increased Critical Strike Chance and Multiplier against Marked enemies.
	Mark on Hit Support - Linked Mark is applied on Hit against Rare and Unique enemies.
	Lifetap Support - Assassin's Mark costs Life and no Mana.

[UTILITY] Immortal Call setup
	Immortal Call - Causes you to take less Physical and Elemental Damage for a brief moment.
	Automation - Immortal Call is triggered whenever it's off-cooldown.

[MOBILITY] Shield Charge setup
	Shield Charge - The mobility Skill you can use to traverse the terrain with haste.
	Faster Attacks Support - Movement Speed while using Shield Charge is increased alongside Attack Speed.
	Lifetap Support - Shield Charge costs Life instead of Mana. Momentum is an alternative.

[UTILITY] Blood Rage
	Blood Rage - More Attack Speed, Life Leech, and Frenzy Charges on Kill. The Life Drain should be manageable.

[UTILITY] Clarity
	Clarity - Keep it at level 1. Watcher's Eye has a god mod for it that reduces the Mana Cost of all skills. You can also replace it with  Vitality, there's the Watcher's Eye mod for instant Life on Hit with Vitality that's also great.

5. Gear Setup

It's a CoC build so it's quite complex to assemble. You need to cap your Crit Chance and then look for the Critical Strike Multiplier. Note that Damage over Time Multiplier does nothing for this build due to Perfect Agony, but you can still benefit from the regular Damage over Time, Poison Damage, and Ailment Damage or Duration. Invest in Cooldown Recover Rate you need even more damage; check how much of it you would need to reach the next breakpoint and have this stat have an actual effect. We have it capped at 7.58 casts per second, which is not very high. Also, note that Lancing Steel of Spraying has a fixed Fire Rate per swing that's independent of your Attack Speed. You can create more sources of these Projectiles with high enough Attack Speed, and increasing the number of Projectiles only makes them last longer. Increasing the Gem Level of Soulrend is also a good way to gain DPS, but there are not a lot of opportunities for it in this setup. You will struggle with Mana Cost so try to reduce it with all means necessary. Mana on Hit and Instant Leech will help you here, but the Cost alone makes it difficult anyhow. Reservation Efficiency is good for the same reason. 139 Strength will be needed for Shield Charge and Immortal Cry. Your defense is built on Maximum Life, Evasion, a bit of Energy Shield with Ghost Dance, 100% Spell Suppression Chance, and maybe Blind and Endurance Charges if you can find a way to integrate them into the build, which we will explain how to do. You also Hit a lot of enemies every second so any source of instant Life on Hit is invaluable. You need no Accuracy.

(Helmet) Rare Helmet - Go for the Evasion base Helmet with Suppression, Maximum Life, and a lot of Elemental Resistances. For the Eldritch mods, we recommend Reduced Mana Cost of Attacks and Mana Reservation Efficiency or increased Duration of Ailments on Enemies.

Min. requirements: +100 to maximum Life +80% to Total Elemental Resistances Spell Suppression Chance Optional affixes:  Attributes  Chaos Resistance increased Mana Reservation Efficiency of Skills

(Body Armour) The Covenant - It adds tons of Chaos Damage to your socketed Skills, which directly increases Poison DPS. If you don't have it yet, just get a Rare Armour with Life and Resistances.

Socketed Gems are Supported by Level 29 Added Chaos Damage +(20-30) to Intelligence (210-250)% increased Energy Shield 10% increased maximum Life Skills gain a Base Life Cost equal to 100% of Base Mana Cost

(Weapon) Rare Sword - One-Handed Sword with the Implicit for Crit Multiplier would be great. Its Affixes must add some more Global Crit Multiplier, Attack Speed to reach the Trigger Rate cap, and there must also be the Crafted Prefix that makes your Attacks unavoidable. You don't need much else.

Min. requirements: increased Attack Speed Hits can't be Evaded Global Crit Multiplier Optional affixes: Attributes Resistances

(Off-hand) Rare Shield - Shield is a source of basic defenses that we already listed. Note that Shaper or Hunter-influenced Shields may have a special Suffix for local Mana Reservation Efficiency and with it, you won't need Enlighten Support.

Min. requirements: +90 to maximum Life +40% Elemental Resistances Spell Suppression Chance Optional affixes: Chaos Resistance Attack Speed Socketed Gems have #% increased Reservation Efficiency Movement Speed

(Gloves) Asenath's Gentle Touch - A popular choice among Poison builds. It Curses enemies with Temporal Chains on Hit, grants some basic stats, and detonates enemies on kill. You can Corrupt them for a chance for one extra Maximum Frenzy Charge.

+(20-30) to Intelligence +(60-80) to maximum Life +(60-80) to maximum Mana Curse Enemies with Temporal Chains on Hit Non-Aura Curses you inflict are not removed from Dying Enemies Enemies near corpses affected by your Curses are Blinded Enemies Killed near corpses affected by your Curses explode, dealing 3% of their Life as Physical Damage

(Boots) Rare Boots - Keep Boots simple, just the basic defensive stats with Movement Speed will be enough. For Eldritch mods you should get increased Cooldown Recovery Rate or Faster Poison, and Action Speed or Chaos Resistance.

Min. requirements: +90 maximum Life 30% increased Movement Speed +80% to Total Elemental Resistances Optional affixes: Spell Suppression Chance Attributes Cooldown Recovery Rate

(Boots) Ralakesh's Impatience - Pair it up with Olesya's Delight and Replica Badge of the Brotherhood. The lack of Maximum Life, Movement Speed, and other mods you can find on Rare Boots is a major downside and so these Boots are highly optional.

+(15-25)% to Cold Resistance +(15-25)% to Chaos Resistance Count as having maximum number of Endurance Charges Count as having maximum number of Frenzy Charges Count as having maximum number of Power Charges

(Belt) Rare Belt - Use a Rare Belt if you need Maximum Life, Resistances, and Strength. In most cases, we recommend Olesya's Delight.

Min. requirements: +100 maximum Life +80% to Total Elemental Resistances Strength Optional affixes: increased Maximum Life Chaos Resistance Flask modifiers Cooldown Recovery Rate

(Belt) Olesya's Delight - Grants 8% more Damage with Poison per Frenzy Charge, which you will probably have 7 or even 10 of. You will no longer gain Frenzy Charges which is bad if you don't want to use Ralakesh's Impatience.

(15-25)% increased Stun and Block Recovery +(600-700) to Evasion Rating +(40-60)% to Cold Resistance (8-12)% increased Movement Speed +1 to Maximum Frenzy Charges Modifiers to Minimum Frenzy Charges instead apply to Minimum Affliction Charges Maximum Affliction Charges is equal to Maximum Frenzy Charges Gain Affliction Charges instead of Frenzy Charges

(Amulet) Rare Amulet - The only redeeming quality of a Rare Amulet is the possibility to gain a lot of global Crit Multiplier with Maximum Life, Resistances, and Attributes. Life on Hit is also great.

Min. requirements: +80 Maximum Life +40% to Elemental Resistances Critical Strike Multiplier +1 to Level of All Choas Skill Gems Optional affixes: Life per enemy Hit with Attack Attributes Chaos Resistance

(Amulet) Replica Badge of the Brotherhood - A lot of players lean towards this Amulet for additional Maximum Endurance Charges, which were improved in patch 3.25. You can't really Fortify yourself, but you can generate Endurance Charges with Enduring Composure from a Small Cluster Jewel.

+(16-24) to Dexterity and Intelligence Your Maximum Endurance Charges is equal to your Maximum Frenzy Charges +1 to maximum Fortification per Endurance Charge (7-10)% increased Cooldown Recovery Rate of Travel Skills per Frenzy Charge (20-25)% chance to lose a Frenzy Charge when you use a Travel Skill (20-25)% chance to lose an Endurance Charge when you gain Fortification

(Amulet) Ungil's Harmony - Despite being an Assassin you will struggle with Crit Chance, especially if your budget is low. This Amulet grants tons of Crit Chance, some Life, and Attributes. The downside does not apply.

+(16-24) to Dexterity and Intelligence (250-350)% increased Global Critical Strike Chance Your Critical Strikes do not deal extra Damage +(30-50) to maximum Life +(30-50) to maximum Mana 40% increased Stun and Block Recovery

(Amulet) Replica Dragonfang's Flight - The obvious choice for Spell builds due to the abundance of various utility mods and one for damage of a specific Skill, Soulrend in our case.

+(10-16) to all Attributes +3 to Level of all <Random Skill> Gems +(5-10)% to all Elemental Resistances (5-10)% increased Reservation Efficiency of Skills Items and Gems have (10-5)% reduced Attribute Requirements

Recommended Anointments: Charisma Savagery Dreamer

(Ring) Rare Rings - Your non-Unique Ring has to have Strength, Maximum Life, Resistances, and a crafted Prefix that lowers the Mana Cost of all Skills by 7.

Min. requirements: +90 Maximum Life +40% to Elemental Resistances Non-Channelling Skills have -7 to Total Mana Cost Strength Optional affixes: Attributes Chaos Resistance

(Ring) Anathema - You will apply 5 Curses - Temporal Chains, Despair, Enfeeble, Punishment, and Assassin's Mark. Anathema is needed for that.

+(15-25) to maximum Energy Shield +(30-40) to Intelligence (10-15)% increased Cast Speed (10-20)% chance to gain a Power Charge when you Cast a Curse Spell Your Curse Limit is equal to your maximum Power Charges

(Jewel) The Light of Meaning - If you can afford one, we recommend The Light of Meaning with increased Chaos Damage. Socket it near Ghost Dance of Fervour.

Passive Skills in Radius also grant 6% increased Chaos Damage

(Jewel) The Balance of Terror - The build lacks Cooldown Recovery Rate which is not a problem because it doesn't have Hit Rate to match it. If you want to increase your trigger rate, you need 52% Cooldown Recovery Rate in total, which is found on Boots and Belt. Get this specific Balance of Terror and cast Temporal Chains every 10 seconds if it would help you reach 52%.

(20-25)% increased Cooldown Recovery Rate if you've cast Temporal Chains in the past 10 seconds Inflict Withered for 2 seconds on Hit if you've cast Despair in the past 10 seconds

(Jewel) Rare Jewels - Jewels are your source of Maximum Life, Attack Speed if you need it, and Critical Strike Multiplier, especially Critical Strike Multiplier for Spells.

Recommended affixes: increased maximum Life Attributes Resistances increased Attack Speed Critical Strike Multiplier for Spell Damage Chance to Poison

(Jewel) Watcher's Eye - You're using Malevolence and Grace. You may also host level-1 Clarity to unlock the one specific mod on a Watcher's Eye that reduces the Mana Cost of all Skills.

(4-6)% increased maximum Energy Shield (4-6)% increased maximum Life (4-6)% increased maximum Mana <Two or Three random aura modifiers>

(Jewel) Large Cluster Jewel - One or Two Large Chaos Damage Cluster Jewels with the notables one can usually find in Poison builds are required.

Recommended affixes: 1 Added Passive Skill is Touch of Cruelty 1 Added Passive Skill is Unwaveringly Evil 1 Added Passive Skill is  Wicked Pall 1 Added Passive Skill is Unholz Grace

(Jewel) Medium Cluster Jewel - Quick Gateway increases Crit Chance, Movement, and Attack Speed. Basics of Pain increases Crit Chance and damage. You can find them on Medium Critical Strike Cluster Jewels.

Recommended affixes: 1 Added Passive Skill is Quick Gateway 1 Added Passive Skill is Basics of Pain

(Jewel) Small Cluster Jewel - Enduring Composure is here if you need to generate Endurance Charges. It is also present on some Megalomaniac Medium Cluster Jewels, mixed in with other useful Notables for Reservation Efficiency, Crit Chance, Poison Damage, and so on.

Recommended affixes: 1 Added Passive Skill is Enduring Composure

(Tincture)  Grasping Nightshade - That's how we plan to apply Withered. Use it against bosses and turn it on only for a second or two. It also inflicts Grasping Vines and Blinds enemies, which is desirable with high Evasion. The other way to Wither is to use The Balance of Terror.

25% chance to Blind Enemies on Hit with Melee Weapons (25-35)% increased Effect of Blind from Melee Weapons Melee Weapon Hits Inflict (2-3) Withered Debuffs for 2 seconds (20-30)% chance to inflict a Grasping Vine on Melee Weapon Hit

Other suggested Flasks and Tinctures: Life Flask with Bleeding immunity/removal Silver Flask with reduced Effect of Shock on you Jade Flask with increased Evasion Rating Quicksilver Flask with increased Movement Speed Diamond Flask with increased Crit Chance

If you have any other build requests, please leave that in the comments below.

Pictures used in this article are the intellectual property of Grinding Gear Games.