Spell 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 . In Warlords of Draenor . Critical Damage and Critical Heals in PvP combat now deal 150 % of the normal spell / ability effects ( down from 200 % ) . In Mists of Pandaria . All spells and abilities will crit for double damage , baseline . There are a few exceptions where crits can get larger , but the default is x 2 . 0 for everyone . Increasing Spell Crit . Spell critical strikes have a generally low chance of occurring , however , you can increase your crit chance in certain ways : Base Spell Crit . The base chance to critically strike with spells is based on the Intellect attribute and a class specific constant . 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 % . Formula . For a level 80 character : Note : Using spell crit effectively . When choosing between equipment with higher spell critical strike or higher + spell damage , there are some things to consider : 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 ; Shaman s , Mage s , and Paladin s saving mana on spell crits , and Holy Priest s and Shaman s 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 .