Flash of Light is a level 4 paladin ability, designed to be the Holy Paladin's quick cast heal. It is considerably faster than [Holy Light], but is the least efficient of the two spells. A Holy Paladin who casts Flash of Light too much risks running out of mana.
Guarded by the Light (paladin honor talent) (Protection honor talent)
Tips and tricks
Flash of Light is a fast but expensive heal. It should only be used when speed is the most important consideration (ie someone is about to die, and won't live long enough for Holy Light to go off) and when [Holy Shock] is not available.
[Sacred Shield]: When a paladin casts Flash of Light on a target with this buff, they also now place a heal over time effect on the target, healing that target for 100% of the Flash of Light amount over 12 seconds.
[The Art of War]: Now only applies to melee critical hits, but will make your next Flash of Light or [Exorcism] instant.
"[Exorcism] has a cast time of 1.5 seconds but can be used on players again. ...we are changing The Art of War to make not only Flash of Light instant, but also Exorcism. Choose healing or damage." (source)
Patch 3.0.3 (2008-11-04):[Infusion of Light] now affects Flash of Light too, reducing its cast time down to zero and can be used while moving.
Patch 2.4.2 (2008-05-13): Flash of Light and Holy Light (old) will now work properly with castsequence macros.
Patch 2.3.0 (2007-11-13):[Blessing of Light]: Lower ranks of Flash of Light and Holy Light (old) are now properly penalized when used with this Blessing.