Nature's Grace, Haste, and Cast Times

EDIT: observations about Nourish, Wrath, and the GCD; May 6 2009
EDIT: GotEM 3.3 link; Oct 14 2009



Nature's Grace reduces your casting time during the proc by 20%. The base cast times (not accounting for gear, buffs OR GotEM) with the proc are such:

• Healing Touch: 3.0 -> 2.4 seconds
• HT w/ Naturalist: 2.5 -> 2.0 seconds
• HT w/ Naturalist + Glyph: 1.0 -> 0.8 seconds
  
• Regrowth: 2.0 -> 1.6 seconds
• Nourish: 1.5 -> 1.2 seconds
• Revive: 10 -> 8 seconds
  
• Rebirth: 2.0 -> 1.6 seconds


• Starfire: 3.5 -> 2.8 seconds
• Starfire w/ SW: 3.0 -> 2.4 seconds
• Wrath: 2.0 -> 1.6 seconds
• Wrath w/ SW: 1.5 -> 1.2 seconds

**For cast times accounting for 3.3 Gift of the EarthMother talent changes rather than NG, please see this post**


Nature's Grace and Spell Haste
Here, I am expanding the cast-time calculations from the list above to account for spell haste. The calculation for hasted spell-casting at level 80 according to WoWwiki is:

HastedCastTime = BaseCastTime /(1 + (% SpellHaste / 100))

With 20% extra from NG, where:
BaseCastTime^NG = BaseCastTime - (BaseCastTime x 0.2) = (BaseCastTime x 0.8)
then,

HastedCastTimeNG = (BaseCastTime x 0.8) /(1 + ( % SpellHaste/100))

• Note: Applying this 20% before or after your own spell haste does not matter, like it did with the old 0.5 second flat reduction (which had to be applied before accounting for haste). I tested applying it both before and after the haste, from haste ratings of 0 to 1650, and they had the exact same results. HastedCastTime^NG = [ (BaseCastTime) /(1 + ( % Spell Haste/100)) ] * 0.8 = (BaseCastTime x 0.8) /(1 + ( % Spell Haste/100))

Using this HastedCastTime^NG formula and converting for Haste Rating at level 80, you can compare your haste rating with various spell/talent/proc combinations to see what the cast time would be:


I shaded the standard GCD as it scales with haste. "NG" is for the spells being cast under the effects of Nature's Grace. The GCD itself will be reduced by Nature's Grace procs; the reduced GCD timer follows the same line in the above graph as the hasted Nourish (until it reaches the 1-second GCD limit), plus some additional buffer time granted by individual latency.

What this means is that Nourish and talented Wrath will not clip your GCD, even under the effects of NG procs.


Proc Duration
Another small change is that the 20% reduction to cast times will now last for 3 seconds, rather than only affecting the very next spell you cast (that is not an insta-cast) within 15 seconds. Because of this, you will likely get two spells off (sans Revive) with this cast time reduction before the proc wears off, assuming you are not casting any insta-casts during the short proc. This is certainly a boon for balance druids.

Resto druids:
The original 15-second duration provided much more leeway to make use of the haste around applying lots of HoTs, and having this cut to 3 seconds may result in a loss of the buff at times without it being used by a spell other than insta-casts. We should consider, however, that since it does reduce the GCD during those 3 seconds, it is allowing us to cast more HoTs in that time as well, barring the 1-second-minimum GCD limit.


Short of the Long
With the Nature's Grace proc now scaling with spells rather than being a flat rate, your longer spell casts will see a much larger reduction, and your short spells a shorter reduction which will prevent some of them clipping the GCD as they once did. Both your normal haste and the NG-procced haste will affect your GCD just as much as they do your normal spellcasts, so your Nourish and talented Wraths will not clip it.

The proc has NO internal cooldown, so it will proc on each and every spell critical (except for channeled crits such as those from hurricane). This can offset the shorter duration by chain-proccing during a series of crits.

I consider this talent to still be essential to any balance druid as well as any resto druid who finds themselves casting regrowth, swiftmend, and/or nourish with any kind of regularity. While WG, lifebloom, and rejuvenation may be our most-used heals, nourish's boosted place as a flash heal for use when swiftmend is on cooldown makes this talent quite useful, and the fact that the proc will reduce your GCD by 20% around any HoTs cast within those few seconds of duration are what makes this talent truly shine among the trees.