“If you are in a raid and are fortunate enough to be tossed an innervate, should you switch to a high spirit weapon, or a high int weapon, to get the best mana gain from the innervate?”
I have been asked that question a lot lately. The short answer: As a holy priest, it doesn’t matter! Do not switch weapons at all. You will get no benefit from switching, so don’t waste the money, the mats, or the bag space on keeping another enchanted weapon with you just for innervates.
And now the long answer/explanation:
Innervate is a druid spell, castable on any friendly target. Here is what it does:
Increases the target’s Spirit based mana regeneration by 400% and allows full mana regeneration while casting. Lasts 20 sec.
Now, in plain English, an innervate will return five times your out-of-five-second-rule regen from intellect/spirit for 20 seconds, and you get this whether you are chain casting spells or not. (Note: mp5 does NOT count towards this, just your regen from spirit/intellect).
If you mouse over the mana regen stat on your character sheet (or armory page), the “while not casting” number is what you would use, minus the straight mp5 from gear. Innervate gives you five times your out-of-combat mana regen every 5 seconds, for 20 seconds (so, four times). So ultimately, you will be taking that number and multiplying it by 20. That should be a pretty big number.
A holy priest on the low end of the gear-spectrum at level 70 would expect that out-of-combat mana regen number (not counting straight mp5 from gear) to be about 400 mp5. A single innervate would return 8k mana to that priest, likely the whole mana pool at that gear level.
I made a test case of a priest in dungeons blues (no epics or gear from professions!), only green gems, no enchants, self-buffed only, no potions/food/elixirs/flasks. This priest, in very mediocre gear, has 407 intellect and 493 spirit. A single innervate returns about 9.3k mana to the priest, and this priest only has 8.4k mana! If this priest were to get buffed with an arcane int buff, then the mana returned from innervate would increase to 9.7k!
… and none of this even figures in your straight mp5 on your gear, which continues to tick upward at its usual rate.
The point is that after you get past a certain minimum level of gear, your mana return from innervate will exceed your mana pool. Therefore, it doesn’t matter what kind of weapon you have. Provided your gear doesn’t suck, an innervate will completely fill your mana pool.
Don’t believe me? Try it yourself! Do the math!
InnervateMana = [OOCmanaRegen - gearMP5] x 20
Or, an alternate equation:
InnervateMana = 100 * (0.001 + sqrt(Int) * Spirit * 0.009327)
Compare that number to your mana pool. Which is bigger? :)
A rough minimum at which an innervate will not completely fill your mana pool is around 400 intellect and 445 spirit (fully buffed). With buffs, these are easily obtainable amounts, even at low gear levels.