Flash Heal

Flash Heal is a quick, quite expensive heal with a moderate healing output. In this post, you'll be able to see and compare a few priest spells' mana efficiency and time efficiency. In order to make these post relevant to priests of all Levels, Item Levels and with different amounts of Spell Power, Haste & Base Mana, I've decided to exclude Spell Power, Base Mana & Haste of my calculations. By doing this, you can't view any correct amounts in neither Healing Ouput, Mana Cost, Cast Time, Healing Per Mana nor Healing Per Second but you can however compare the different values between different spells.

Healing Output: 332.657% of Spell Power = 3.32657 * [Spell Power Value]
Mana Cost: 4.1% of Base Mana = 0.041 * [Base Mana Value]
Cast Time: 100-[Haste Value]% of Base Cast Time = (1-[Haste Value]) * 1.5 sec

Mana Efficiency = Healing Output / Mana Cost = 3.32657/0.041 ≈ 81.136 HPM (Healing per Mana)
Time Efficiency = Healing Output / Cast Time = 3.32657/1.5 ≈ 2.217 HPS (Healing per Second)

Below you can find the comparable values of some priest spells. Assumptions: [spell=47540] is completely channeled and [spell=596] heals 5 targets.

Categories

[spell=2060]

Flash Heal

[spell=47540]

[spell=596]

Healing Output

3.3264

3.32657

3.024

11.0832

Mana Cost

0.02

0.041

0.012

0.071

Base Cast Time

2.5

1.5

2.0 (Channeled)

2.5

HPM

166.320

81.136

252

156.101

HPS

1.331

2.217

1.512

4.433

EDIT [08/13/14]: Updated posts for latest Beta Build and made post relevant to all Discipline [class=5]s by excluding certain variables.

Flash Heal being a 1.5 second spell, I'd assume the coefficient is (1.5 / 3.5) = ~0.43, ie 43%.

Cataclysm:

This is a Priests' fast, expensive heal. It has a short cast time, heals for a rather large amount, but the mana cost is very high. You should only use this if your target will die before you can land a Heal or Greater Heal spell.

Disc and Shadow, not all priests. Holy priests still have Flash Heal after 28.

Flash Heal is the spell that a Discipline Priests should use between Penance.

This is because:

1. Flash Heal has a lower chance of overhealing.
   
2. Divine Aegis and Rapture does not benefit from overhealing done.
   
3. With Glyph of Flash Heal and Rapture, it burns very low amounts of mana.
   

The only benefit Greater Heal has to Discipline Priests is that the larger heal makes a larger shield. And as point 2 says, over healing does not make much of a benefit.

whats the % from +healing this spell gets? without empowered healing talents.

[class=5] PvP Healing 2P Bonus [spell=33333] cause Prayer of Mending trigger Holy Spark on the initial target, increase healing received from the [class=5]'s next Flash Heal within 10 sec by 50%.
[spell=123111] reduce mana cost of Flash Heal by 20%.

Flash Heal's healing increased by 25% for Holy, Discipline [class=5] ([spell=87336]).

[spell=109186] give each Penance (Discipline only), Circle of Healing (Holy only), Prayer of Mending, Prayer of Healing, Flash Heal, Binding Heal, [spell=2050], [spell=2060], Smite a 15% chance to trigger [spell=114255], make next Flash Heal within 20 sec:

• 
  
• free
• 
  
• instant
• 
  

limit 2 charges.

[spell=63733] can be considered as the resources for Holy [class=5]; one can have 2 stacks of [spell=63733] max.
it generate by (they all modified by [spell=77485]):

• 
  
• Flash Heal (+1)
• 
  
• Binding Heal (+1)
• 
  

when [class=5] have stacks of [spell=63733], these spells can be cast to consume all stacks of [spell=63733] (cast time & mana cost reduced by 20% for each stacks of [spell=63733] consumed):

• 
  
• [spell=2060]
• 
  
• Prayer of Healing
• 
  

enter [spell=81208] cause Flash Heal:

• 
  
• healing increased by 25%
• 
  
• refresh the duration of the [class=5]'s Renew on the target.
• 
  

for Discipline [class=5], each Flash Heal (modified by Mastery: Shield Discipline):

• 
  
• increase healing the target received from the [class=5] by 10%, stack up to 3 times ([spell=47517]).
• 
  
• reduce the duration of the Weakened Soul debuff on the target by 2 sec ([spell=89488]).
• 
  

[spell=89485] cause next Flash Heal:

• 
  
• mana cost reduced by 25%
• 
  
• guaranteed to be critical
• 
  

enter [spell=109964] cause Flash Heal no longer heal but instead create absorption shields that last 15 sec.

[spell=131566] cause during [spell=109964], reduce mana costs of Flash Heal by 50%.

Shadow [class=5] can cast Flash Heal but can NOT cast without cancel Shadowform.

Not only Disc, all priests.

Well, that would explain why I felt something was off. That really sucks since I was enjoying playing that spec.