Flash of Light used to be my bread and butter spell. This blog is Flash of Moonfire because Flash of Light was such a key part of my repetoire as a holy paladin ever since I first hit 70 and started healing Karazhan.
But when Cataclysm hit I had trouble figuring out where I'd put it on my bars. The tilda, numbers 1-6, and F1-F6 are the keys I bind things to, with occasional Ctrl or Shift combinations. Flash of Light used to be number 2 since I hit it so often. Then it moved to F2 to be a little more out of the way since I didn't use it that often. Now...
Well, it's still on my bars, but it's not bound to anything. That's probably bad, but its usefulness has become so far out of sight and out of mind that I have trouble thinking of moments where someone died because I didn't use it.
The thing is... it doesn't heal that much for the mana cost (making it an expensive proposition for what you get out of it) and it still has a cast time unless there's an Infusion of Light proc (making it's usefulness while moving limited).
I've been doing arena the majority of Season 9 and since the start of Season 10. I've seen other holy paladins run themselves dry casting Flash of Light too many times while I'm still at 90% or more mana. Whereas when I need an emergency heal and Holy Shock and Word of Glory are on cooldown, I hit Divine Favor for that 20% haste and crit and chug out a speedy Divine Light or two (perhaps combined with Aura Mastery to ensure no interruption). I figure if I'm going to spend the mana I'm going to get the most health I can for it.
I'm sure there's room for a Flash of Light in there. Again, it'd be instant with an Infusion of Light proc, but as a cast time spell I just wouldn't use it. An IoL-enhanced Divine Light goes by so fast that 90% of the time it's too fast for my opponents to interrupt (gladiator level I am not, so YMMV).
Then this week I did some Firelands raiding with the second 10-man team in my guild as a fill-in healer. I know these fights on my druid, but for those I've always been dps or a tank. I had little to no experience healing them, so I was surprised by how much faith the raid leader had in me, suggesting we two-heal several fights, considering that my paladin had only the Firelands cape and a bizarre mix of BWD, troll dungeon, and PvP gear.
I thought that perhaps as I was doing PvE raiding I would find a use for Flash of Light, a reason to keybind it again, but I didn't.
It's not that there were no wipes that were my fault, being rather scrubbish for the duties I was assigned, but they weren't because I didn't get a quick heal off. I'm quick with my Lay on Hands and I'm not afraid to use it if I think a tank's gonna die.
Wipes were more due to missing the Smouldering Devastation cue on Beth'talic (I'm not usually on the web, let alone as a healer), being in the wrong place on Alysrazor (until recently I always tanked that fight so I had no concept of where the caster adds spawned and lost a dps and a tank because of range issues), and there was the occasional, for some reason or other I didn't think the tank's health was going to drop that fast so I wasn't ready with a heal.
But we cleared 6/7 and I two-healed Alysrazor and Rhyolith so at the very least I know I'm not bad. I was just on a bit of a learning curve, and I was the only healer who didn't let someone die to Torment on Baelroc so I was rather happy about that.
Getting back to Flash of Light though... I still didn't see when to use it. I thought maybe Baelroc would be the boss.
Torment's a nice stacking debuff that eventually chews through dps the higher it goes. But it ended up that I would Holy Shock, Word of Glory, and then roll almost immediately into Divine Lights to make sure no one dropped.
My mana was hurting almost every Firelands boss (inexperience healing the fights combined with not as geared as the rest of the raid), so if I needed a "save" I wanted it to be Lay on Hands because at least that would give me some mana back.
I guess I don't use Flash of Light because I try very hard not to be in the position where Flash of Light would be appealing to me; namely where someone's going to die and that little sliver of health would make it worth the cost of using it.
In PvP I use Holy Shock and Word of Glory as much as possible. If I use cast time spells I'm either using them under an IoL proc (making them very fast and hard to interrupt), I Aura Mastery to make them uninterruptable, or I prepare to cancel the cast if the possibility of getting interrupted exists and then cast again after the interrupt is wasted. It's rare I do unprotected casts in arena, and if I do it's because my partner is probably going to die in the next couple of seconds if I don't and all my cooldowns have been burned.
In PvE there are multiple healers and the the damage intake doesn't seem to warrant it. Tanks get hit too hard for Flash of Light to make much of a difference. And if they're dps or another healer, there is typically enough time between damage bursts to allow HoTs or a Holy Light to save them.