As I discussed in Multistrike and You, two new secondary stats are being added in Warlords of Draenor. The second and somewhat simpler of these is Readiness. As always, anything may change between now and release.
Readiness is basically Haste for cooldowns. Just as Haste reduces casting time, Readiness reduces cooldown time. The reduction is handled the same way, through division: 30% Haste divides cast times by 1.3, and 30% Readiness divides cooldown times by 1.3. We can already see this in effect with Frost Bomb's Haste-based cooldown reduction.
Different Specs, Different Cooldowns
Like Mastery, balancing the value of Readiness across specs will involve turning at least one, and likely two knobs. The first is the affected cooldowns. Not every cooldown will be reduced; those that are will be specified in tooltips. For example, Arcane may see reductions in the cooldowns of Arcane Power, Evocation and Mirror Image, while Frost sees a reduction in the cooldowns of Icy Veins and Frozen Orb.
The second is the use of a coefficient. Just as 600 Mastery Rating converts to 2% Icicle damage and 1.5% Ignite damage, we will likely find that a given amount of Readiness Rating converts to, for example, a 2% reduction in cooldown time for one spec and a 1.5% reduction in cooldown time for another.
By combining these two variables, the devs intend to make the value of Readiness reasonably similar for every spec.
So let's imagine the Arcane and Frost examples I gave above, with each spec having 30% Readiness. We would see cooldown reductions as follows (assuming the existing base cooldowns did not change):
- Arcane Power: 90 / 1.3 = 69.23, a reduction of about 21 seconds for a cooldown of about 1:09.
- Evocation: 120 / 1.3 = 92.31, a reduction of about 28 seconds for a cooldown of about 1:32.
- Mirror Image: 180 / 1.3 = 138.46, a reduction of about 42 seconds for a cooldown of about 2:18.
- Icy Veins: 180 / 1.3 = 138.46, a reduction of about 42 seconds for a cooldown of about 2:18.
- Frozen Orb: 60 / 1.3 = 46.15, a reduction of about 14 seconds for a cooldown of about 0:46.
There really isn't much to it. It's simple, but it offers clearly different playstyle effects than the other secondary stats. A player who focused on Haste and Multistrike would have a pretty different experience from a player who focused on Crit and Readiness.
Have any questions? Feel free to comment!