At low levels, this is usually the warlock's fastest option for dealing damage to groups of mobs. Be aware however that this will generate a large amount of threat.
Very situational, for it pulls threat and costs Soul Shards. Mainly useful in instances for AoE.
This is a very powerful spell that combines the natures of flame and water. It calls forth the essence of fire and delivers it through massive thunderheads of vapor and brimstone, creating an actual firestorm. This spell is very destructive, and will cause damage to any foes and buildings in its sphere of influence. Use this spell with care, for the rain of fire knows no friends.[2]
Rain of Destruction is one of Gul'dan's Heroic Abilities in Heroes of the Storm. It differs from Rain of Fire in that it summons green fel meteors, each dealing a separate amount of damage.
No longer causes a stun after hitting a target three times.
No longer requires Immolate to be present to generate Burning Embers.
Rain of Fire's damage over time will now hit every 1 second, down from 2 seconds. The damage animation for the damage over time effect will no longer always display.
Hotfix (2012-12-10):Damage from Rain of Fire will no longer prevent enemy players from capturing flag objectives.
Patch 5.0.4 (2012-08-28): Now an Affliction and Destruction specialization ability at level 21 (was a level 18 ability for all warlocks). Duration reduced from 8 to 6 sec.
Patch 4.2.0 (2011-06-28): Rain of Fire has a new spell effect.
Patch 4.1.0 (2011-04-26): Damage has been increased by 25%.
Patch 4.0.3a (2010-11-23): Damage has been increased to be more comparable to other area-of-effect abilities.
Patch 4.0.1 (2010-10-12): Now learned at level 18 (was 20).
Patch 3.3.3 (2010-03-23): Rain of Fire has a new graphic.
Patch 3.0.8 (2009-01-20): Rain of Fire has a new animation.
Patch 2.4.0 (2008-03-25): The casting bar will now display properly when casting Rain of Fire with spell haste.
Patch 2.2.0 (2007-09-25): This spell is now affected by area damage caps. Its bonus damage coefficients have also been increased.
Patch 1.7.0 (2005-09-13): Fixed a bug where area of effect periodic damage spells were being resisted more frequently than they should have been when casting lower level ranks of the spell (affected spells included Rain of Fire).
Patch 1.1.0 (2004-11-07): Duration, mana cost, and damage slightly reduced, deals its damage in more frequent intervals.