Spell critical strike

This page is about spell critical strikes only. For physical, see Critical strike.

Spell critical strike (often abbreviated as "spell crit") is when a spell or magical effect (most damaging spells, healing spells, some damage over time effects) has an increased effect. To see your chance to critically strike with spells, open your character pane and view your spell stats. Mobs are unable to get critical strikes with spells.

Spell Crit Damage

Spell critical strikes deal 150% normal damage without talents. However, most spellcasting classes have talents to increase it, most commonly to 200% normal damage. Spell critical heals will only heal for 150% of their normal amount.

Increasing Spell Crit

Spell critical strikes have a generally low chance of occurring, however, you can increase your crit chance in certain ways:

• Attributes
• Talents (some classes)
• Equipment
• Critical strike rating gems
• Enchantments
• Glyphs
• Potions (temporary)
• Buffs (temporary)

Base Spell Crit

The base chance to critically strike with spells is based on the Intellect attribute and a class specific constant.

	Intellect per crit %			Class Specific Constants
Class	Level 60	Level 70	Level 80
Druid	60.0	80	166.6667	1.85
Hunter	?	?	166.6667	3.6
Mage	59.5	80	166.6667	0.91
Paladin	54	80.05	166.6667	3.336
Priest	59.2	80	166.6667	1.24
Shaman	59.5	80	166.6667	2.2
Warlock	60.6	81.92	166.6667	1.701

Spell Critical Strike Rating

The easiest method to increase the chance of a critical strike is to equip gear with the attribute "Improves critical strike rating by 'x'." For some classes, spell critical strike rating is of less value.

Unlike Intellect, spell critical strike rating increases the chance to get a critical strike equally for all classes. At level 70, 22.08 spell critical strike rating increases the chance to critically hit with a spell by 1%. At level 80, 45.91 critical strike rating increases the chance to critically hit with a spell by 1%.

Critical Strike Rating Required Per 1%
Level 60	Level 70	Level 80
14	22.08	45.91

Formula

For a level 80 character:

 Crit Chance % = ((Intellect / 166.6667) + Class Constant) + (Crit Rating / 45.91)

Note:

• Talents that affect the crit chance of "all spells" (ie: [Conviction]), or talents that specifically affect spells of a certain school (ie: [Critical Mass], Holy Power), directly add to the calculated "Crit Chance %" on the character pane.
• Talents that only affect the spell crit chance of a specific spell (such as [Incineration] and Force of Will) are NOT included in the spell "Crit Chance %" on the character pane.
• Mousing over the "Intellect" value in your character pane will show you the Intellect portion of your spell "Crit Chance" (ie: "Increases Spell Critical Hit by x.xx%"). This works out to the "(INT/166.667)+ClassConstant" portion of the formula.
• Death Knights receive no bonus Spell Crit Chance from intellect and so also do not have a class constant.
• Rogues and Warriors have a spell critical strike chance of 0% no matter what their Intellect is. However, the Warrior ability [Thunder Clap] uses Spell Critical Strike Rating to determine the chance to crit. Rogue poisons use this and Spell Damage as well.

Using spell crit effectively

When choosing between equipment with higher spell critical strike or higher +spell damage, there are some things to consider:

• Some classes have abilities or talents which proc off of spell critical strikes, as do some items.
• Spell crit can lead to more unpredictable damage. As such, it can be powerful, but unreliable.
• In a group, a string of spell crits can lead to pulling aggro off the tank (and possibly a dead caster).
• Many spells, particularly untalented DoTs, cannot crit. Spells that have a direct damage component and a DoT component (e.g. [Holy Fire]) are able to crit on the direct damage component but not the DoT. The same is true of HoTs. Notable exceptions are mages with  [Glyph of Living Bomb] and warlocks with the [Pandemic] talent.
• As a general rule, even though there are exceptions, increasing your pure spell damage is more effective damage wise than increasing your critical strike rating.

Spell hit or spell crit?

All other things being equal and without considering talents, an 1% increase in spell crit chance will result in a gain of 0.5% of a spell's base damage, whereas a 1% increase in spell hit chance will give a 1% increase of a spell's base damage. As long as no other effects come into play (like Ignite, which would make +crit slightly more important), +spell hit rating is more effective than +spell crit rating. But although increasing +spell hit over 99% is not a complete waste if using binary against a resist chance (since in that case the resist chance works as a reduction of the hit chance), in general a 99% spell hit chance will be sufficient for most casters.

If a Mage has taken the Ice Shards or Spell Power talent to increase the crit damage to 200%, hit and crit are basically equal, similar to the situation as it exists with physical damage. Other classes have similar "increase critical strike damage by 50%" talents. There is still debate whether spell casting is based on a one-roll system (like "normal" melee) or not, although there is currently overwhelming evidence that it is a "two-roll" system - hit rolled for first, followed by a roll for crit.

Another important factor to consider are the many effects which can proc from spell crits. These include a Warlock's [Improved Shadow Bolt]; Shamans, Mages, and Paladins saving mana on spell crits, and Holy Priests and Shamans proccing an armor buff on heal crits (see Inspiration).

For most of the Burning Crusade, spell crit rating was nearly worthless for Shadow Priests. With Patches 3.0.2 and 3.0.3, it became a much more valuable stat, becoming roughly equal to spell hit on a percent-to-percent based comparison.

For dedicated healers, +spell hit rating is essentially worthless. Spells cast on friendly targets (such as heals, buffs, and dispels/cures) always hit. However, +spell crit rating improves the chance of getting a critical effect on helpful and harmful spells alike. Although it is not advisable to rely on the extra healing granted by critical effects from healing spells, a lucky critical heal in a fight going badly could mean the difference between life and death for a group member, or even the entire group. Even if a critical heal results in an overheal, this extra healing has no impact on the threat generated by the healer. Additionally, there are talents available to Priests, Druids and Shamans which grant a short-duration armor buff to the recipient of a critical heal. When given the choice between +spell hit rating and +spell crit rating, a primary healer will always benefit from more +crit, while they will see little if any benefit from +spell hit rating. Just to be clear, if an item says "Improves spell critical strike rating", it will also improve the crit chance of healing spells.

Paladins also have the [Illumination] talent, which gives them back 30% of the mana cost of the healing spell they crit on. Shamans have a similar talent, [Improved Water Shield], which consumes a [Water Shield] charge on a crit. Since this essentially amounts to an average reduction in mana costs, it's common for Paladins and Shamans to stack +spell crit rating, and find themselves in the area of 25% crit chance.

See also

• Combat
• Combat rating system