Five Second Rule / Irrelevant for Cataclysm
 

[top]Five Second Rule Explained

The "Five Second Rule" (sometimes shortened to 5SR or FSR) is the name given to the mechanic that dictates no mana will be regenerated naturally (that is, via base regeneration + Spirit modifier) for 5 seconds after a spell is cast. While under the effect of the five second rule, you regenerate an amount of mana displayed by the character sheet or Armory as "mana regenerated while casting", which is the sum of mana restored from MP/5 items plus any passive mana regeneration granted from talents or abilities. This amount is "always on" and will regenerate its value regardless of whether or not you are casting.

Your full natural regeneration combined with mana restored from MP/5 items is referred to in the Armory or in-game tooltip as "mana regenerated while not casting".

Mana is always regenerated in two-second increments. As of 2.2, the MP/5 value is pro-rated over the 2 seconds. What this means is that the amount of regen is averaged over the two seconds. For example if you activated an ability that disrupted your mana regeneration such as an instant spell, in the second half of the tick, you would receive one tick's worth of "while not casting" regen and one tick's worth of "while casting" regen. This means that abilities that could occasionally tick too few or too many times such as Evocation will now always return the same amount of mana.

Spells with no mana cost (such as Lifetap) or spells that are made to cost no mana through a proc (such as a spell that consumes a Mage Clearcasting or Druid Omen of Clarity) will not put the player in the five second rule. Abilities such as Shaman Clearcasting that do not reduce the spell cost by 100% are treated as normal spells.

Talents such as Meditation or abilities like Mage Armor that state "allows ##% of your mana regeneration to continue while casting" simply restore that percentage of your normal mana regeneration even while you are under the effects of the five second rule. Any such abilities that can be combined do so additively (Mage Armor and Arcane Meditation combine for 30+15= 45% of normal mana regeneration). This amount may not exceed 100% (i.e. Darkmoon: Blue Dragon, Innervate and Evocation do not stack with anything else). These talents will grant you a higher "mana regenerated while casting" value, but not a higher "mana returned while not casting" value. This is an important distinction to make when weighing the effectiveness of such abilities in conjunction with Spirit against MP/5.

It is critical to note that the Five Second Rule is disrupted only when mana is spent. This means that a channeled spell disrupts full regeneration when it is cast, while a spell that can be cancelled to have no effect like Fireball will not spend its mana until the end of the cast. While you do not regenerate any mana while channeling a spell with a long duration (such as Mind Control), any time spent channeling the spell will count towards the five seconds that are needed to elapse before entering full regeneration.

Some examples of minimizing time inside the five second rule include:

• Canceling unnecessary heals.
• Casting a long cast time spell followed by an instant spell (doing this in reverse will cause a good deal more time outside of full regeneration).
• Combining spells that spend their mana up front with spells that spend their mana as the spell finishes. For example, since Arcane Missiles is a channeled spell which spends its mana at the start of the channeling, a mage may cast Arcane Missiles followed by Fireball or Scorch which spend their mana at the end of the spell as normal. This will cause the mage to be briefly be outside the five second rule (the time it takes for Fireball to cast) and he or she will gain a small amount of mana while continuing to do damage.

[top]Mana Regen Formula

The amount of mana regenerated while not casting is the same for all classes as of patch 2.4 and uses the following formula:

ManaRegen per 5 seconds = (0.001+(Spirit * BASE_REGEN[LEVEL] * (Intelligence^0.5))*5

For level 70 characters, BASE_REGEN is 0.009327. This value has been determined from datamining. (Thanks Whitetooth)

Clarification please:

"...any time spent channeling the spell will count towards the five seconds that are needed to elapse before entering full regeneration."
So, for example, when a 3 second channel spell finishes, the caster has only two seconds remaining before hes out of 5SR.

If that is true, why is the example of casting Arcane Missiles before Fireball more efficient? Assuming the caster is out of combat to start (and not at full mana), casting Fireball first would keep him out of 5SR during cast time, and then could continue to do damage with Arcane Missiles while coming out of 5SR. In this scenario, there is no penalty to mana regeneration for casting Arcane Missiles as the player would be under the 5SR from Fireball regardless.

As soon as AM finishes the player is in full mana regeneration for the duration of fireball's cast time. Your assumption of out of combat is a fallacy. It's not an article about "Best Practices: Mage Rotation For Three Shotting Mobs While Leveling".

Do we have this number for level 80 yet?

0.005575

Base regen at lvl 80
 

I tested this number using the stats from my druid, and I find it to be incorrect.
My unbuffed stats are 869 int, 888 spirit and 777 mp5 while not casting, giving this equation (inequality):
776.500 <= (0.001+(888 * BASE_REGEN[80] *(869^0.5)))*5 <= 777.499

0.0059326 <= BASE_REGEN[80] <= 0.0059402