Caustic Arrow

Borrowing a bit of toxic chemistry from the secretive Oriath Necromancers guild, a skilled archer infuses their arrowhead with a wicked venom. Once enchanted, the arrow will explode violently when it impacts a target, showering both foes and the surrounding area with a cloud of choking death. Anything living caught in the cloud will suffocate quickly, suffering heavy chaos damage until they move far away.

Description on the official Path of Exile website

Caustic Arrow is a bow attack that fires an arrow dealing chaos damage and exploding in a caustic cloud. Enemies standing within it receive a debuff that deals chaos damage over time. The caustic cloud does not poison and is therefore not affected by poison-related modifiers.

Skill functions and interactions

• Caustic Arrow will explode either at the targeted location or on the first monster or obstacle it hits.

• Multiple projectiles: additional projectiles added will cause additional caustic clouds, but debuffs from multiple clouds do not stack.

• Piercing: piercing Caustic Arrow projectiles will cause additional clouds each time they hit and will receive the chaos damage bonus any time they impact an enemy.

• Projectile damage: passive nodes and gems (such as Slower Projectiles SupportSlower Projectiles SupportSupport, Projectile
  Icon: J
  Level: (1-20)
  Cost & Reservation Multiplier: 120%Requires Level 31Supports projectile skills.Per 1% Quality:1Superior2Anomalous3DivergentSupported Skills deal 0.5% increased Projectile DamageSupported Skills deal 0.75% increased Projectile Damage to nearby EnemiesProjectiles Fired by Supported Skills have 3% chance not to Pierce EnemiesSupported Skills have (20-30)% less Projectile Speed
  Supported Skills deal (10-19)% more Projectile DamageThis is a Support Gem. It does not grant a bonus to your character, but to skills in sockets connected to it. Place into an item socket connected to a socket containing the Active Skill Gem you wish to augment. Right click to remove from a socket.) that increase projectile damage will increase both the damage on hit and the area of effect damage.

• Concentrated Effect: Concentrated Effect SupportConcentrated Effect SupportSupport, AoE
  Icon: o
  Level: (1-20)
  Cost & Reservation Multiplier: 140%Requires Level 18Supports any skill with an area of effect, regardless of whether that skill deals damage.Per 1% Quality:1Superior2Anomalous3DivergentSupported Skills deal 0.5% increased Area DamageSupported Skills have 0.5% less Area of EffectSupported Skills have 0.5% reduced Enemy Stun ThresholdSupported Skills have 30% less Area of Effect
  Supported Skills deal (25-39)% more Area DamageThis is a Support Gem. It does not grant a bonus to your character, but to skills in sockets connected to it. Place into an item socket connected to a socket containing the Active Skill Gem you wish to augment. Right click to remove from a socket. decreases the size of the AoE and increase its damage. However, due to the nature of the skill and the wording of its modifiers, the damage increase will not appear on the tooltip.

• Point Blank: Point Blank does not affect the caustic cloud damage, it only affects projectile attack damage.

• Iron Grip: The strength bonus from the Iron Grip keystone passive does not affect the caustic cloud damage because the cloud is not considered an attack nor is it based on physical damage. The increased projectile damage portion of the Iron Grip SupportIron Grip SupportProjectile, Physical, Support
  Icon: i
  Level: (1-20)
  Cost & Reservation Multiplier: 110%Requires Level 18Supports attack skills that fire projectiles, making the increase to physical melee damage from strength also increase their physical projectile damage.Per 1% Quality:1Superior2Anomalous3DivergentSupported Skills deal 0.5% increased Projectile DamageSupported Skills have 0.5% reduced Attack Speed
  Supported Skills deal 2% increased DamageSupported Skills have 0.5% increased Projectile SpeedStrength's Damage bonus applies to Projectile Attack Damage as well for Supported Skills
  Supported Skills deal (0-38)% increased Projectile DamageThis is a Support Gem. It does not grant a bonus to your character, but to skills in sockets connected to it. Place into an item socket connected to a socket containing the Active Skill Gem you wish to augment. Right click to remove from a socket. will increase the cloud damage, but the strength bonus the support gem shares with the keystone will not apply.

• Accuracy: The projectile attack is subject to accuracy and can miss. However, the explosion will create a caustic cloud and do damage regardless of whether the projectile attack hit or missed. Piercing Caustic Arrow will not create additional clouds if missed.

• Duration: modifiers to duration will affect the duration of the caustic cloud.

• Culling strike: The increased damage from Culling Strike SupportCulling Strike SupportSupport
  Icon: X
  Level: (1-20)
  Cost & Reservation Multiplier: 110%Requires Level 18Supports any skill that hits enemies. If enemies are left below 10% of maximum life after being hit by these skills, they will be killed.Per 1% Quality:1Superior2Anomalous3DivergentSupported Skills have 0-10% Increased DamageSupported Skills deal 3% increased Damage with Hits against Enemies that are on Low LifeRecover 0.1% of Life when Supported Skills Cull an EnemyKill Enemies that have 10% Life or lower when Hit by Supported Skills
  Supported Skills deal (0-38)% increased DamageThis is a Support Gem. It does not grant a bonus to your character, but to skills in sockets connected to it. Place into an item socket connected to a socket containing the Active Skill Gem you wish to augment. Right click to remove from a socket. applies to cloud damage, but the cloud does not kill enemies instantly when they have less than 10% life.

• Curses: Sniper's MarkSniper's MarkSpell, Duration, Curse, Mark
  Level: (1-20)
  Cost: (16-33) Mana
  Cast Time: 0.50 secRequires Level 24Curses a single enemy, increasing the damage they take from projectiles, and making projectiles split when hitting them, to hit other targets around them. You can gain charges for your life and mana flasks by hitting the cursed enemy. You can only have one Mark at a time.Per 1% Quality:1Superior2Anomalous3DivergentCursed enemies take 0.25% increased Damage from Projectile HitsCurse Skills have 1% increased Cast SpeedHits on Cursed Enemies have an additional 2% chance to KnockbackBase duration is (6-9.8) seconds
  Projectiles which Hit Cursed Enemies Split towards (3-4) additional targets
  Cursed enemies take (16-35)% increased Damage from Projectile Hits
  You gain a Mana Flask Charge when you Hit Cursed Enemy, no more
  than once every 0.5 seconds
  You gain a Life Flask Charge when you Hit Cursed Enemy, no more
  than once every 0.5 secondsPlace into an item socket of the right colour to gain this skill. Right click to remove from a socket. requires the target to be hit. The caustic cloud won't be affected by it. DespairDespairSpell, AoE, Duration, Chaos, Curse, Hex
  Level: (1-20)
  Cost: (16-33) Mana
  Cast Time: 0.50 sec
  Radius: 22Requires Level 24Curses all targets in an area, lowering their chaos resistance and increasing damage over time they take. All hits will deal added chaos damage to the cursed enemies.Per 1% Quality:1Superior2Anomalous3DivergentCursed enemies take 0.5% increased Damage from Damage Over Time effects0.5% increased Effect of CurseSpell Hits have 0.5% chance to Hinder Cursed Enemies with 30% reduced Movement Speed for 4 secondsBase duration is (9-10.9) seconds
  Cursed enemies have -(20-29)% to Chaos Resistance
  Cursed enemies take (15-25)% increased Damage from Damage Over Time effects
  Adds (9-46) to (12-57) Chaos Damage to Hits against Cursed Enemies
  Curse gains 10 Doom per second if you Cast this Spell yourself
  +(0-10) to radiusPlace into an item socket of the right colour to gain this skill. Right click to remove from a socket. does affect the cloud.

Gem level progression

Level			Mana Cost	Damage Effectiveness	Attack Damage	Base Duration	Chaos Damage per sec	% of Physical Damage as Chaos	Radius	Exp.	Total Exp.
1	1	0	6	55%	55%	N/A	8.8	N/A	N/A	0	0
2	2	0	6	55%	55.5%	N/A	10.1	N/A	N/A	70	70
3	4	16	6	56%	56%	N/A	13.1	N/A	1	308	378
4	7	22	6	56%	56.5%	N/A	18.4	N/A	1	1554	1932
5	11	31	7	57%	57%	N/A	27.8	N/A	1	6667	8599
6	16	41	7	57%	57.5%	N/A	44	N/A	2	26047	34646
7	20	50	7	58%	58%	N/A	61.9	N/A	2	49725	84371
8	24	58	7	58%	58.5%	N/A	85.4	N/A	2	95714	180085
9	28	67	8	59%	59%	N/A	116.2	N/A	3	169595	349680
10	32	75	8	59%	59.5%	N/A	156.3	N/A	3	283759	633439
11	36	83	8	60%	59.9%	N/A	208.5	N/A	3	453996	1087435
12	40	92	8	60%	60.4%	N/A	275.9	N/A	3	703128	1790563
13	44	100	9	61%	60.9%	N/A	362.7	N/A	4	1061223	2851786
14	48	109	9	61%	61.4%	N/A	474.1	N/A	4	2065870	4917656
15	52	117	9	62%	61.9%	N/A	616.9	N/A	4	2507110	7424766
16	56	125	9	62%	62.4%	N/A	799.3	N/A	5	5798936	13223702
17	60	134	10	63%	62.9%	N/A	1031.8	N/A	5	15083919	28307621
18	64	142	10	63%	63.4%	N/A	1327.6	N/A	5	27792735	56100356
19	67	148	10	64%	63.9%	N/A	1600.8	N/A	6	43869739	99970095
20	70	155	10	64%	64.4%	N/A	1927.1	N/A	6	242081556	342051651
21	72	159	11	65%	64.9%	N/A	2179.2	N/A	6	N/A	N/A
22	74	N/A	11	65%	65.4%	N/A	2462.7	N/A	7	N/A	N/A
23	76	N/A	11	66%	65.9%	N/A	2781.5	N/A	7	N/A	N/A
24	78	N/A	11	66%	66.4%	N/A	3139.9	N/A	7	N/A	N/A
25	80	N/A	12	67%	66.9%	N/A	3542.6	N/A	8	N/A	N/A
26	82	N/A	12	67%	67.4%	N/A	3995	N/A	8	N/A	N/A
27	84	N/A	12	68%	67.9%	N/A	4503.1	N/A	8	N/A	N/A
28	86	N/A	12	68%	68.4%	N/A	5073.4	N/A	9	N/A	N/A
29	88	N/A	13	69%	68.9%	N/A	5713.4	N/A	9	N/A	N/A
30	90	N/A	13	69%	69.4%	N/A	6431.6	N/A	9	N/A	N/A
31	91	N/A	13	70%	69.8%	N/A	6822.8	N/A	9	N/A	N/A
32	92	N/A	13	70%	70.3%	N/A	7237.1	N/A	10	N/A	N/A
33	93	N/A	14	71%	70.8%	N/A	7675.8	N/A	10	N/A	N/A
34	94	N/A	14	71%	71.3%	N/A	8140.3	N/A	10	N/A	N/A
35	95	N/A	14	72%	71.8%	N/A	8632.2	N/A	11	N/A	N/A
36	96	N/A	14	72%	72.3%	N/A	9152.9	N/A	11	N/A	N/A
37	97	N/A	15	73%	72.8%	N/A	9704.1	N/A	11	N/A	N/A
38	98	N/A	15	73%	73.3%	N/A	10287.7	N/A	12	N/A	N/A
39	99	N/A	15	74%	73.8%	N/A	10905.4	N/A	12	N/A	N/A
40	100	N/A	15	74%	74.3%	N/A	11559.3	N/A	12	N/A	N/A

Item acquisition

Upgrade paths

This item can be acquired through the following upgrade paths or vendor recipes:

Amount	Ingredient	General Notes	Type
3	The Bitter BlossomThe Bitter Blossom3Level 21 Chaos Gem Quality: +23% CorruptedThe pain you feel is of no consequence, it is evolution, to be made whole within something greater.	random corrupted superior level 21 Chaos gem with 23% quality	Automatic
8	Dying AnguishDying Anguish8Level 19 Gem Alternative Quality: +19%Moribund, he gazed upon the journey taken as blood trickled down his chin. His eye closed on the city ahead that he would never call home.	random level 19 gem with 19% alternative quality	Automatic
1	Gemcutter's IncubatorGemcutter's IncubatorAdds an incubated Quality Gem item to an equippable item Item drops after killing # monstersQuality GemRight click this item then left click an item to apply it. The Incubated item drops after killing a specific number of monsters.	random superior gem	Automatic
6	The FoxThe Fox6Level 20 Gem"Masters of wit, strength and cunning. To survive the harsh winters, you must be like the fox." - Ezomyte Proverb	random level 20 gem	Automatic
3	Gemcutter's PromiseGemcutter's Promise3Superior Gem Quality: +20%"I swore to use my position to help the people. What good is power when it just accumulates on the already-powerful?" - Erasmus, Imperial Gemcutter	random superior gem with 20% quality	Automatic
1	The VoidThe Void1Reach into the Void and claim your prize.	random divination card set exchange	Automatic

Quest reward

This item is given as a quest reward for the following quests:

Class →	Witch	Shadow	Ranger	Duelist	Marauder	Templar	Scion
Quest ↓
Enemy at the Gate Act 1	✗	✗	✓	✗	✗	✗	✗

Vendor reward

This item can be bought at the listed NPC vendors, after completing the following quests:

Class →	Witch	Shadow	Ranger	Duelist	Marauder	Templar	Scion
Quest ↓
Enemy at the Gate Act 1 Nessa	✗	✓	✓	✓	✗	✗	✓
A Fixture of Fate Act 3 Siosa	✓
Fallen from Grace Act 6 Lilly Roth	✓

Alternate skill effect

Name	Cost	Description
Tentacle Caustic Arrow EffectTentacle Caustic Arrow EffectSkill Gem EffectYour Caustic Arrow becomes an area of ethereal purple tentacles.	120	Replaces the standard effect on a Caustic ArrowCaustic ArrowAttack, Projectile, AoE, Duration, Chaos, Bow Level: (1-20) Cost: (6-10) Mana Attack Damage: (55-64)% of base Effectiveness of Added Damage: (55-64)% Projectile Speed: 3260 Radius: 20Fires an arrow which deals chaos damage in an area on impact, and spreads caustic ground. Enemies standing on the caustic ground take chaos damage over time.Per 1% Quality:1Superior2Anomalous3Divergent0.5% increased Area of Effect1% chance to inflict Withered for 2 seconds on Hit1% of Physical Damage Converted to Chaos DamageDeals (55-64.4)% of Base Attack Damage Base duration is 2 seconds Deals (8.8-1927.1) Base Chaos Damage per second 60% of Physical Damage Converted to Chaos Damage Modifiers to Projectile Damage apply to this Skill's Damage Over Time effect +(0-6) to radiusPlace into an item socket of the right colour to gain this skill. Right click to remove from a socket. gem with an area of ethereal purple tentacles. Preview

Related helmet enchantments

The following helmet enchantments affect Caustic Arrow.

Name		Stats	Spawn Weighting
Enchantment Caustic Arrow Damage 1	66	25% increased Caustic Arrow Damage	helmet 75 default 0
Enchantment Caustic Arrow Damage 2	75	40% increased Caustic Arrow Damage	helmet 75 default 0
Enchantment Caustic Arrow Duration 1	66	20% increased Caustic Arrow Duration	helmet 75 default 0
Enchantment Caustic Arrow Duration 2	75	30% increased Caustic Arrow Duration	helmet 75 default 0
Enchantment Caustic Arrow Area Of Effect 1	66	16% increased Caustic Arrow Area of Effect	helmet 75 default 0
Enchantment Caustic Arrow Area Of Effect 2	75	24% increased Caustic Arrow Area of Effect	helmet 75 default 0
Enchantment Caustic Arrow Wither On Hit 1	66	Caustic Arrow has 14% chance to inflict Withered on Hit for 2 seconds base Duration	helmet 75 default 0
Enchantment Caustic Arrow Wither On Hit 2	75	Caustic Arrow has 20% chance to inflict Withered on Hit for 2 seconds base Duration	helmet 75 default 0

Version history

Version	Changes
2.6.0	Caustic Arrow gains 1 additional unit of radius every 5 levels. No longer gain increased area of effect radius.
2.1.0	Poison Arrow has been renamed to Caustic Arrow as part of the poison changes. The damage of this skill has been increased by around 37% at level 1, but reduced by around 42% by level 20. This reduction is more than compensated for by supporting the skill with the new supports. Caustic Arrow's mana costs have been increased, from 5 to 8 at level one, and from 13 to 16 at level 20.
2.0.0	Reduced the mana cost across all levels. Now grants 0.5% increased area of effect radius per 1% of quality (was 1% per 1% quality). Damage increased by approximately 26% at gem level 20.
1.3.0	Poison Arrow can now damage totems.
1.1.2	Damage has been increased by 8% at level 1, scaling up to an increase of 75% at level 15 of the gem.
1.0.6	Poison Arrow's damage has been increased at higher levels. It now does roughly 35% more damage at gem level 15.
1.0.3	Damage progression has been increased. It is now around 15% better at level 15 than it was in 1.0.2.
1.0.2	Early levels of Poison Arrow have had their damage reduced by around 35%.
0.9.13	It now starts off around 85% stronger at level 1 and is about 1% weaker at level 15.
0.9.12	Rebalanced its mana cost progression to reflect the fact that it does damage in a comparable way to Spells.
0.9.9	The size of the Poison Arrow clouds now scale with their Area of Effect radius properly.
0.9.7	Improved the effects of Poison Arrow.
0.9.5g	Fixed a bug where the Poison Arrow cloud would appear where you clicked even if the arrow was stopped before then by a wall.
0.9.5	Fixed Poison Arrow so that damage from the degeneration is scaled properly for PvP.
0.9.4	Increased the damage.
0.9.2	Poison Arrow does more damage at higher levels than before.
0.8.7	Poison Arrow does additional chaos damage on the actual arrow itself now, in addition to the cloud damage.
0.8.5	Added new skill prototype: "Poison Arrow" (Fires an arrow which explodes in a cloud of poison. Enemies who enter the cloud are poisoned for a short time, taking chaos damage)