If another warlock has an Immolate active on the target, the Conflagrate button will be ungrayed. However, you cannot cast Conflagrate unless you have an Immolate active on the target.
Curse of the Elements increases damage done by Conflagrate by 10%/13% based on rank of Curse.
It was recommended to use this spell just right before the Immolate or [Shadowflame] expires, but after patch 4.0.1, this spell directly deals %60 of the periodic damage of your Immolate on the target, and it no longer consumes your Immolate and will not work off Shadowflame.
The listed damage of this spell and the actual damage will usually be different because Emberstorm (+3/6/9/12/15% dmg of all fire spells; including Conflagrate) is a commonly taken talent in the tier before.
The [Glyph of Conflagrate] will reduce the cooldown of this spell to 8 seconds. Keep in mind conflagrate has a cooldown of 10 seconds, and immolate has a duration of 15 seconds. Its a common practice to spam the Immolate spell while waiting for the cooldown of Conflagrate, and since Conflagrate no longer consumes Immolate, you can refresh your Immolate with [Fel Flame] for keeping up the cycle.
Patch changes
/Patch 4.0.1 (12-Oct-2010): Changed. Instantly deals fire damage equal to 60% of your Immolate's periodic damage on the target. 40% DoT effect removed. Consumption effect removed. Relation to Shadowflame removed.
Patch 3.3.2 (2010-01-02): The damage-over-time effect of Conflagrate has been increased to 40% of the spell's total damage, up from 20%.
Patch 3.3.0 (08-Dec-2009): Redesigned. This talent now consumes an Immolate or Shadowflame effect on the enemy target to instantly deal damage equal to 9 seconds of Immolate or 8 seconds of Shadowflame, and causes additional damage over 3 seconds equal to 3 seconds of Immolate or 2 seconds of Shadowflame. In addition, the periodic damage of Conflagrate is capable of critically striking the afflicted target.
Patch 3.1.2 (2009-05-19): Updated: Consumes an Immolate or Shadowflame effect on the enemy target to instantly deal damage equal to 12 seconds of your Immolate, or 8 seconds of your Shadowflame.
Hotfix (2009-04-15): "We have hotfixed the damage of the Warlock spell Conflagrate from 100% to 70% of Immolate's total periodic damage instantly. The tooltip may still show 100% until a future update though."
Patch 3.1.0 (14-Apr-2009): Spell now works similar to Swiftmend, consuming an Immolate or Shadowflame effect on the target and dealing damage based on the strength of that effect. Reduced to a single rank.
Patch 2.3.0 (13-Nov-2007): The Immolate debuff will now always be removed correctly when this spell is cast.
12 October 2010 +, 2 January 2010 +, 8 December 2009 +, 19 May 2009 +, 14 April 2009 +, 13 November 2007 +, 22 May 2007 +, 10 October 2005 +, 13 September 2005 + and 7 June 2005 +