Cast On Critical Strike Support

For the awakened variant, see Awakened Cast on Critical Strike Support.

Cast on Critical Strike (commonly referred to as CoC) is a support gem that causes linked spells to trigger when the player scores a critical strike with the attack skill it is linked to.

Skill functions and interactions

There is an internal cooldown to how fast spells can be triggered, as of patch 3.5 the cooldown is 150ms, or roughly 6 casts per second given optimal conditions.

In case of multiple spells linked to one attack skill this support will alternate the spell being triggered.

Trigger order: Trigger gems and their linked skills are cast in a certain order that depends both on which item it is equipped on and which socket the skills are in. If there are trigger gems in each equipped item, the order of operation will be:

Main hand ⇒ Amulet ⇒ Helm ⇒ Off hand ⇒ Body armour ⇒ Gloves ⇒ Boots

The linked sockets also follow a specific order, as follows:

1 ⇒ 2
    ⇓
4 ⇐ 3
⇓
5 ⇒ 6

Cooldown Time: When a supported spell is successfully cast, it and all supported spells of the same name are put on cooldown for 150 milliseconds. This means that a given spell can only trigger once per critical strike, and reduces the effect of linking multiple copies of the same spell to this support (especially when it is at a higher gem level). It is important to note that this cooldown does not apply to the gem as whole; you can trigger multiple spells within the 150 millisecond cooldown time as long as they are different.

Gem level progression

Level				More Spell Damage	Exp.	Total Exp.
1	38	40	27	20%	0	0
2	40	41	29	21%	388734	388734
3	42	43	30	22%	477437	866171
4	44	45	31	23%	583786	1449957
5	46	47	33	24%	710359	2160316
6	48	49	34	25%	1355511	3515827
7	50	51	35	26%	1138877	4654704
8	52	53	37	27%	1368233	6022937
9	54	55	38	28%	1638338	7661275
10	56	57	39	29%	1956648	9617923
11	58	58	41	30%	3655184	13273107
12	60	60	42	31%	3017327	16290434
13	62	62	43	32%	3576232	19866666
14	64	64	44	33%	4231667	24098333
15	65	65	45	34%	2395078	26493411
16	66	66	46	35%	8421063	34914474
17	67	67	46	36%	16159983	51074457
18	68	68	47	37%	41170367	92244824
19	69	69	48	38%	86794448	179039272
20	70	70	48	39%	157405063	336444335
21	72	72	50	40%	N/A	N/A
22	74	N/A	N/A	41%	N/A	N/A
23	76	N/A	N/A	42%	N/A	N/A
24	78	N/A	N/A	43%	N/A	N/A
25	80	N/A	N/A	44%	N/A	N/A
26	82	N/A	N/A	45%	N/A	N/A
27	84	N/A	N/A	46%	N/A	N/A
28	86	N/A	N/A	47%	N/A	N/A
29	88	N/A	N/A	48%	N/A	N/A
30	90	N/A	N/A	49%	N/A	N/A
31	91	N/A	N/A	49%	N/A	N/A
32	92	N/A	N/A	50%	N/A	N/A
33	93	N/A	N/A	50%	N/A	N/A
34	94	N/A	N/A	51%	N/A	N/A
35	95	N/A	N/A	51%	N/A	N/A
36	96	N/A	N/A	52%	N/A	N/A
37	97	N/A	N/A	52%	N/A	N/A
38	98	N/A	N/A	53%	N/A	N/A
39	99	N/A	N/A	53%	N/A	N/A
40	100	N/A	N/A	54%	N/A	N/A

Strategy

Linking with other skills

At a bare minimum, a Cast On Critical Strike setup will require three gems: an attack, Cast On Critical Strike itself, and a spell to be triggered. This generally leaves at most three other supports that may be linked. If possible, the supports should both increase the number of times Cast On Critical Strike triggers, and increase the effectiveness of the triggered spells. Note that Cast On Critical Strike cannot trigger more than once per frame, so staggered hits (e.g. multiple projectiles) are preferred to simultaneous hits (e.g. most area of effect damage) which will only proc at most once per attack.

Projectile

By far the most popular family of Cast on Critical Strike setups, projectile Cast On Critical Strike focuses on the projectile keyword. Popular attacks for this purpose include:

• : Naturally staggers hits, automatic pierce, allows the use of melee weapons at range.
• : Causes a large number of sequential hits per attack.
• : Naturally produces power charges.
• : Naturally large number of projectiles.
• : Piercing on initial arrow(s) and produces three times as many subprojectiles.
• : Five projectiles plus the initial hit.
• : Magma balls generally hit on different frames, causing a large number of hits.
• : Three projectiles plus the initial hit.

Support skills that affect both the number of hits and crits projectile attacks generate and affect projectile spells include:

• for and certain spells

Useful projectile spells and their support limitations include:

• : Does not explode on pierce, fork, or chain.
• : Not affected by pierce, fork, or chain; hit rate limited per cast, not per projectile.
• : Little benefit from but more from .
• : Does not explode on pierce, fork, or chain.
• : Benefits from .
• : Already pierces in first form.
• : Less benefit from but more from .

A second spell may satisfactorily be used in place of a support.

Area of Effect

Some attacks have advantageous built-in area of effect:

• : The area of effect is progressive, not instant, allowing multiple casts per attack. However, it can only get one cast against a single target.

This works well with spells which have Area of Effect component, such as:

Support gems which can benefit this setup are:

Minion

Another possibility is to use attacks to trigger minions, which benefit from attack supports. In addition to the projectile skills listed before, we have some other good choices:

• : Causes two hits per attack, only uses main hand when dual-wielding.
• : Causes staggered hits rapidly.

Minions generally have poor critical strike capabilities, so critical strike supports are not as effective as they are with projectile spells. Good attack supports include:

• : While it does not increase procs much due to the splash happening on a single frame, it greatly improves minion effectiveness.
• : For Melee attacks.
• : Improves minion accuracy greatly, removes the need for accuracy on gear.
• Since patch 2.0.0, increasing gem quality on no longer grants 1% increased chance of critical strike per 1% gem quality, and instead gives a simple 1% increased accuracy per 1% gem quality. Accuracy is a desirable stat, as one cannot crit what they cannot actually hit. However, the loss of the critical strike stat granted from gem quality means this is no longer a top-tier supporting gem choice. Losing the critical strike chance affects not only the minion gem in the link; as mentioned minions have poor critical strike capabilities, and were only the minion affected there would be no noticeable difference after patch 2.0.0. Of course, this is not the case, as the critical strike chance also affects the attack you are using to proc CoC (the 'trigger' spell), and any other spells to be cast on critical strike (the 'triggered' spells) in the link. This essentially results in less CoC procs overall, less damage from your trigger spell, and less critical hits from your triggered spells as well. This triple-whammy means that Additional Accuracy Support is no longer the top-tier option that it once was, with or without an attached minion and minion-buffing support gems. When considering only the minion, and ignoring any of the triggering/triggered spells & CoC proc rate, the golem/minion is likely perform better with a Faster Attacks Support instead of Additional Accuracy Support; minions will miss more, but making far more attacks per measurement of time. No longer recommended in a CoC link since patch 2.0.0 except to fill in accuracy you desperately need due to poor passive tree and/or gear options.

Most minions are severely capped in number and thus do not benefit much from the high proc rate of Cast On Critical Strike. However, there is one that works well:

Passives and gear

Since "double-dipping" on support gems is key to an effective Cast On Critical Strike setup, having a 5- or 6-link is more important than it is for most builds.

Unlike conventional attack builds, attack damage is not necessary on passives or gear, though it can be helpful in situations where the linked spells are less effective. Attack speed and critical strike chance are the two essential statistics.

Some base item types tend to have better critical hits per second than others:

1. Wands
2. Claws, Daggers
3. Sceptres, Thrusting Swords
4. Bows, Staves, 1H Swords

Possibly good uniques to use include:

Item	Perfect crits/s
	9.08%
	11.17%
	15.50%
	17.25%
	13.16%
	14.28%
	10.47%
	10.47%
	12.19%
	10.75%
	12.09%
	10.00%
	16.67%
	63.00%

Related modifiers

The following modifiers are related to Cast On Critical Strike Support:

Legacy mods

The list below displays Cast On Critical Strike Support related modifiers where all spawn weights have been set to zero.

Related unique items

The following unique items are related to Cast On Critical Strike Support:

Version history

Version	Changes
3.15.0	Supported Skills now deal 20-29% more Spell Damage (previously 20-39%).
3.5.0	Cast on Critical Strike now has a 150ms cooldown.
2.4.0	For Cast on Critical Strike, , and , only one skill can be triggered per trigger event. The spell that is triggered is determined based on the order in which it is socketed, and will cast supported spells in sequence, even across multiple attacks. These items and skills also have cooldowns which limit how often a skill is cast. These cooldowns apply per-triggered-skill, rather than applying to the trigger gem itself. Cast on Critical Strike now has a 500ms cooldown, and will now only trigger one spell per frame when you critically strike. It now has 100% chance to trigger casts when you critically strike. It now has 20% more spell damage at level 1, tapered up to 39% at level 20 (1% per level).
1.3.0	Cast on Critical Strike's cooldown has been increased from 0.01 seconds to 0.05 seconds.
1.2.0	The chance to cast has been reduced by a flat 20% at all levels.
1.0.5	Cast on Critical Strike now has a 10 millisecond cooldown. The chance to cast supported skills has been increased by a flat 20%.
1.0.0e	The Cast on Crit support gem has been renamed to Cast on Critical Strike
1.0.0	Cast on Crit has been added to the game.