Stun

This page is about the game mechanic. For the support gem, see Stun (support gem).

Whenever a player or monster takes damage from a hit, there is a chance they will be stunned. A stun interrupts whatever that creature was doing while a brief animation is played.

Neither damage over time nor reflect can cause stun.

Mechanics

"Stun Duration" redirects here. For the passive skill, see Stun Duration (passive skill).

"Stun Recovery" redirects here. For the passive skill, see Stun Recovery (passive skill).

The chance to stun is based off the damage done in a single hit compared to the target's maximum life. The default length of stuns is 350ms.
The duration of stuns can be altered by increased Block and Stun Recovery, increased Stun Duration on enemies, increased Stun Duration with Two Handed Melee Weapons on enemies and similar modifiers.

Whether or not a stun occurs can be calculated using the following formula:

stun_chance [%] = 200 * damage / defender_effective_max_life

In other words, in single-player a enemy will be stunned a mean of two time throughout its lifetime, assuming no regeneration or "wasted" damage.

Where defender_effective_max_life is what the maximum life of the creature would be in a single-player map. Increases to monster life from a party of more than one player do not affect defender_effective_max_life.

For a player with Chaos Inoculation, their defender_effective_max_life is whatever their maximum life would be if they did not have Chaos Inoculation.

If the chance to stun would be less than or equal to 20%, it is ignored, so you need to deal more than 10% of effective maximum life to have a chance to stun. Dealing at least 50% of maximum life will always stun.

Stun threshold

Reduced stun threshold modifiers reduce the value of defender_effective_max_life. For example, 25% reduced Enemy Stun Threshold means the enemy will be treated as if their defender_effective_max_life is only 75% as much as it actually is, increasing the chance that the enemy will be stunned.

When the total Stun Threshold Reduction would be over 75%, it is instead treated as being:

75 + ( Stun Threshold Reduction - 75) * 25 / ( Stun Threshold Reduction -50 )

The net effect on the mean number of stuns during a monster's lifetime is as follows:

• Hyperbolic regime: From 0-75% Reduced Stun Threshold, the mean number of stuns per lifetime increases from 2 to 8, accelerating as it goes.
• Linear regime: Every 3.125% Reduced Stun Threshold past 75% increases the mean number of stuns per lifetime by 1.

Examples

If a player has a total of 110% reduced Enemy Stun Threshold from gear and skills, the actual value that gets used would be:

75 + ( 110 - 75 ) * 25 / ( 110 - 50 )

75 + 35 * 25 / 60

75 + 35 * 0.42

75 + 14.6 = 89.6% reduced Enemy Stun Threshold

Reduced Enemy Stun Threshold	Effective Reduced Enemy Stun Threshold	Minimum Percentage of life a hit needs to deal to stun	Percentage of Life a hit needs to deal to have 100% stun chance
0%	0%	10%	50%
5%	5%	9.5%	47.5%
10%	10%	9%	45%
15%	15%	8.5%	42.5%
20%	20%	8%	40%
25%	25%	7.5%	37.5%
30%	30%	7%	35%
35%	35%	6.5%	32.5%
40%	40%	6%	30%
45%	45%	5.5%	27.5%
50%	50%	5%	25%
55%	55%	4.5%	22.5%
60%	60%	4%	20%
65%	65%	3.5%	17.5%
70%	70%	3%	15%
75%	75%	2.5%	12.5%
80%	79.2%	2.08%	10.4%
85%	82.1%	1.79%	9%
90%	84.4%	1.56%	7.8%
95%	86.1%	1.39%	7%
100%	87.5%	1.25%	6.25%
105%	88.6%	1.14%	5.7%
110%	89.6%	1.04%	5.2%
115%	90.4%	0.96%	4.8%
120%	91.1%	0.89%	4.5%
125%	91.7%	0.83%	4.2%
130%	92.2%	0.78%	3.9%
135%	92.6%	0.74%	3.7%
140%	93.1%	0.69%	3.5%
145%	93.4%	0.66%	3.3%
150%	93.8%	0.62%	3.1%

Stun immunity

• The unique amulet Eye of ChayulaEye of Chayula
  Onyx AmuletRequires Level 20+(10-16) to all Attributes20% reduced maximum Life
  30% increased Rarity of Items found
  Cannot be StunnedNever blinking, always watching.
  
  This item can be transformed with a Blessing of Chayula grants your character immunity to stun.
• The Keystone Unwavering Stance also provides stun immunity, but prevents your character from evading attacks.

Avoiding stun

• As long as a creature has greater than 0 Energy Shield, it has a 50% chance to ignore a stun. This is calculated independently of the creature's chance to be stunned. First the chance to stun is calculated as normal, and if the stun check succeeds and would cause a stun, there is then a 50% chance that the stun can be ignored. An attack that removes energy shield can have its stun avoided, even though energy shield is 0 after damage is applied. You lose with chance to ignore a stun with the Eldritch Battery keystone node.
• The notable node Heart of Oak grants +#% chance to Avoid to avoid being Stunned.
• The notable nodes Practical Application and Nimbleness grants +#% chance to Avoid interruption from Stuns while Casting.

The above modifiers are not doing the same thing, and applies at different times. They are not, and cannot be, additive with each other.

Example

A character with considerable amount of energy shield is continuously casting a spell. The character have following mods:

• +38% chance to Avoid to avoid being Stunned
• +25% chance to Avoid interruption from Stuns while Casting

The character then gets hit that normally would stun the character. However, due to all the avoidance modifiers the actual chance to become stunned is:

 (1 - 0.5) * (1 - 0.38) * (1 - 0.25) = 23.25%