Critical strikes in Path of Exile are a way to deal with increased damage and possibly inflict elemental ailments. Critical strikes are rolled on a per-action basis, not per target. This means that all targets hit by a single action will either be all crit or all not crit. Critical strike chance and critical strike damage multiplier are calculated separately for each spell and weapon attack. 

• Weapon Attacks
• Spells 
• Accuracy 
• Critical Strike Multiplier
• Enemies
• Power Charges
• Reducing Extra Damage from Critical Strikes
• Skill 
• Power Charges
• Calculate the critical strike chance

Weapon Attacks

All weapons list a base critical strike chance, which only affects attacks using that weapon. This base critical strike chance can be increased by various modifiers. According to this equation, critical strike chance equals the base chance plus the additional chance times, one plus the increase. For example, if you have a two-handed axe with a five percent base critical strike chance, and you have 20 increased global, critical strike chances and 20 increased local, critical strike chances, it would be calculated as 5 times 1.2 times 1.2, which gives you 7.2 percent critical strike chance. 

Spells 

Each spell has its own critical strike chance, which is listed in the skill gems description. This chance can be increased by various modifiers. For example, if you have a fireball linked to increased critical strike support at level one, it will give you plus two percent base, as well as 60, increased, so that gives you eight percent base crit that is then scaled by the 60 increased. This works out to twelve point eight percent chance to crit. 

Accuracy 

Accuracy is important when it comes to critical strikes. Accuracy measures the chance for an attack to hit, and accuracy-dependent attacks make a second accuracy check to confirm the critical strike. If the check fails, only a normal hit is dealt. Thus, accuracy can play an important role in the number of critical strikes.

Critical Strike Multiplier

Critical strikes deal more damage than normal based on the critical strike multiplier. All characters have a base, critical strike multiplier of 150 percent. The damage will be multiplied according to critical strike damage equals your base damage times the base, critical strike multiplier, plus additional critical strike multiplier. For example, if you do 100 damage that will then become multiplied times, 1.5 giving you 150 damage.

Enemies

Monsters have a base, critical strike multiplier of 130 percent, and it can be increased via various monsters, affixes, and auras, as well as map mods. This can make monsters hit really hard, so it is important to be aware of these modifiers. 

Power Charges

Power chargers are specifically based on critical strike chance. Each one will give you 40 increased critical strike chances. With a base and three power charges, you have 120 increased critical strike chances. 

Reducing Extra Damage from Critical Strikes

Take percent reduced extra damage from critical strikes is a multiplier. For example, if you had 300 crit multi and the monsters had a mod that said, take 50 reduced extra damage from critical strikes it's as if you only had 150 crit multi, it's not 300 minus 50, it's 300 times 0.5. This means that this modifier is very strong for players, but can be very dangerous if you rely on critical strikes. 

Skill 

The base critical strike chance of skill is usually 6%, with some skills having a higher or lower base critical strike chance. You can then increase the critical strike chance of the skill with support gems such as the Increased Critical Strike Support or the Weapon Elemental Damage Support, as well as certain gear with increased critical strike chance. 

Power Charges

In addition to increased sources of critical strike chance, you may also want to take into account power charges. Power charges are generated when you crit, and they can increase your critical strike chance by up to 40%. This means that if you have 3 power charges, your total critical strike chance would become 160% (100% + 40% x 3 = 160%). This means that your final critical strike chance would be 25.6% (6% x 16 = 25.6%).

Calculate the critical strike chance

To calculate your total critical strike chance, you'll need to add up all of the sources of increased critical strike chance and then multiply them by the base critical strike chance of your skill. For example, if you have a weapon with a 20% increased critical strike chance, a Marble Amulet with a 60% increased critical strike chance, and an Increased Critical Strike Support gem with a 20% increased critical strike chance, your total critical strike chance would be 100% increased critical strike chance (20+60+20=100). This means that your base 6% critical strike chance would now be multiplied by 6 to give you a final critical strike chance of 36%. 

Conclusion

Critical strikes are an important part of Path of Exile and can be a powerful tool when used correctly. It is important to understand the basics of critical strikes and the various modifiers and mechanics that affect them in order to make the most out of your Poe build.