Engulfs you in flames for 10 sec, Rank 2 (Level 56): 12 sec
increasing your spells' critical strike chance by 100% and granting you Mastery equal to 50% your Critical Strike stat. Castable while casting other spells.
"A little fire goes a long way." —Cerripha Sunstreak[1]
Combustion is a level 29 Firemage ability. When activated, it increases critical strike chance with mage spells by 100% and grants Mastery equal to 50% of your critical strike rating.
[Firestarter] causes every cast of Fireball to reduce the remaining cooldown on Combustion by 5 seconds.
Azerite Traits
[Wildfire] causes Combustion to grant the mage additional critical strike rating, and a lesser amount of critical strike rating to up to 4 nearby allies, for 10 seconds.
[Glyph of Smolder] causes the mage to smolder for a few seconds after Combustion ends.
Patches and hotfixes
Retail
Patch 8.0.1 (2018-07-17): Combustion now only affects Mage spells, and no longer interacts with non-mage spells such as damaging trinket procs.
Patch 7.1.5 (2017-01-10): The amount of Mastery granted has been reduced to 50% of Critical Strike rating (was 100%). Rank 2 has been removed and its effects are once again baseline.
Patch 7.1.0 (2016-10-25): Now available at level 40 (up from level 28). Combustion has been split into two ranks, the second rank granting Mastery equal to critical strike rating. Rank 2 is available at level 65.
Patch 7.0.3 (2016-07-19): Redesigned. Now increases critical strike by 100% and Mastery equal to the Critical Strike stat for 10 seconds. Cooldown increased from 45 seconds to 2 minutes.
Previous effect: Resets the cooldown on Inferno Blast and combusts your Ignite on the target, burning for additional damage over 10 sec equal to 8 seconds of Ignite's current damage over time.
Hotfix (2014-11-12): "Combustion is now learned at level 80 (up from level 77)."
Patch 6.0.2 (2014-10-14): Combustion no longer deals direct damage or stuns. Damage dealt has been increased by 100%. Additionally, this ability now replaces [Deep Freeze] for Fire mages.
Patch 5.4.0 (2013-09-10): Combustion on targets affected by the Mage's Ignite now deals additional damage equal to 20% of Ignite's damage per tick (down from 50%).
Hotfix (2012-11-29): "The periodic damage from Combustion has been reduced by 50%."
Patch 5.1.0 (2012-11-27): Periodic damage is now based only on the current Ignite, instead of both Ignite and Pyroblast. Damage has been increased to bring it up to approximately the same level as before.
Hotfix (2012-10-16): "Combustion direct damage that does not crit now causes Heating Up to be removed after a short delay. Additionally, the delay on non-crits removing Heating Up has been increased from 0.25sec to 0.5sec."
Pyroblast and Combustion should combine to do the expected amount of damage and critical damage.
The initial damage of Combustion is now properly affected by Shatter, increasing its crit chance accordingly."
Hotfix (2012-09-12): "Combustion should no longer ignore target damage multipliers when calculating the damage of the Pyroblast DoT on the target."
Patch 5.0.4 (2012-08-28): Combustion is no longer a talent and instead a baseline ability available at level 77. This ability now only counts [Pyroblast] and Ignite (previously counted [Living Bomb]), and will now stun its target. Cooldown reduced to 45 seconds, down from 2 minutes.
Patch 4.3.0 (2011-11-29): Combustion’s periodic damage can now critically hit.
Hotfix (2011-07-26): "Combustion should no longer ignore damage modifiers on a target. As an example, Smoldering Elemental packs in the Firelands should no longer take full damage from Impact’s spread of Combustion, despite these creatures having damage reduction modifiers."
Patch 4.1.0 (2011-04-26): No longer has a global cooldown.
Patch 3.3.3 (2010-03-23): The cooldown on this spell is now 2 minutes, down from 3 minutes.
Patch 3.2.2 (2009-09-22): This talent now also increases the critical strike damage bonus of Fire spells by 50% while it is active. In addition, [Living Bomb] periodic ticks will no longer interact with the count or the charges on the talent.
Patch 3.2.0 (2009-08-04): Fire spell misses will no longer trigger this talent.
Patch 1.12.0 (2006-08-22): Reduced the number of messages that appear in the combat log when using Combustion.
Patch 1.11.0 (2006-06-19): Redesigned. When activated, this spell causes each Fire damage spell you cast to increase your critical strike chance with Fire damage spells by 10%. This effect lasts until you have caused 3 critical strikes with Fire spells. 3 minute cooldown. Previously, it increased the critical strike chance of the next fire spell by 100%, only guaranteeing one critical strike. The cooldown was 5 minutes.
Classic
Hotfix (2020-08-28): Fixed a bug that unintentionally allowed Combustion to apply a permanent buff to crit chance.
[Glyph of Smolder]
[Firestarter], 
[Kindling], 
[Wildfire]
[Fireball], 
[Fire Blast], 
[Phoenix Flames], and 
[Pyroblast] to reduce the remaining cooldown on Combustion by 1 second.
Patch 8.0.1 (2018-07-17): Combustion now only affects Mage spells, and no longer interacts with non-mage spells such as damaging trinket procs. 
Patch 7.1.5 (2017-01-10): The amount of Mastery granted has been reduced to 50% of Critical Strike rating (was 100%). Rank 2 has been removed and its effects are once again baseline. 
Hotfix (2014-11-12): "Combustion is now learned at level 80 (up from level 77)." 
[Deep Freeze] for Fire mages. 
Patch 5.4.0 (2013-09-10): Combustion on targets affected by the Mage's Ignite now deals additional damage equal to 20% of Ignite's damage per tick (down from 50%). 
[Living Bomb]), and will now stun its target. Cooldown reduced to 45 seconds, down from 2 minutes. 
Patch 4.3.0 (2011-11-29): Combustion’s periodic damage can now critically hit. 
Patch 3.3.3 (2010-03-23): The cooldown on this spell is now 2 minutes, down from 3 minutes. 
Patch 1.12.0 (2006-08-22): Reduced the number of messages that appear in the combat log when using Combustion. 
