Soul Fire always critically strikes. In addition, the damage is increased by your critical strike chance.
Generates 30 Demonic Fury.
Soul Fire is a warlock ability learned at level 13 for those with the Demonology specialization. It is a mana efficient, high damage Direct Damage spell, best used as an initial attack for pulling due to its long cast time. In this sense it is similar to the Mage's Pyroblast ability.
This skill has been shown to be one of the most mana-efficient spells.
The long cast time of this spell makes it harder to use in PvP as the time spent casting is time gained for an enemy player to tear you to pieces.
Patch changes
Patch 5.2.0 (5-Mar-2013): Soul Fire now deals 22% more damage.
Patch 4.3.0 (29-Nov-2011): Soul Fire now scales with 72.6% of spell power, up from 62.5%.
Patch 4.2.0 (28-Jun-2011): Soul Fire is now available at level 20, down from level 54.
Patch 3.3.0 (08-Dec-2009): The talent Molten Core in the demonology tree, now has a chance to increase Soul Fire's damage by 6/12/18% and critical strike chance by 5/10/15% when your Corruption deals damage.
/Patch 3.0.2 (14-Oct-2008): Removed the spell's cooldown.
Patch 2.0.3 (09-Jan-2007): The mana cost of "Soul Fire" has been reduced by approximately 45%.