The Basics of Rapid FireRapid Fire: Increases haste by 40% for 15 seconds. 2 min cooldown.
Careful Aim: Increases the critical strike chance of your Steady Shot, Focusing Shot and Aimed Shot by 60% on targets who are above 80% health or while Rapid Fire is active.
In WoD, Careful Aim was modified to include any time that Rapid Fire is up. This completely changed the use of Rapid Fire from a basic increased haste CD to a huge DPS CD with both Crit and Haste bonuses. Where as in MoP we wanted to use Rapid Fire mostly when we were low on focus, in WoD we'll do the opposite, pooling focus so we can use the most Aimed Shots as possible during the buff.
Stacking CDs and Trinkets
During the first tier of WoD, our pre-raid BiS trinket will be Lucky Double Sided Coin. In addition to a good chunk of crit, this trinket includes an on-use Agility buff, with a very convenient 2 minute cool down.
Because this trinket has the same CD as Rapid Fire, for the vast majority of hunters, you'll simply want to macro these two abilities together (See the section on Chim Shot below for an explanation of how you can do better than macro'ing the two together). You may have particular macros you like to use, but for me, it looks something like this:
#showtooltip Rapid Fire
/cancelaura Hand of Protection
/cast Rapid Fire
Note, for those unfamiliar with macros, if you keep your Lucky Double Sided Coin in the upper trinket slot, you'll want "/use 13" instead of "/use 14".
In case I haven't spelled it out lately, the reason you want to always stack these two abilities is the same reason we stack anything as DPSers: damage modifiers multiplied together result in higher total damage than damage modifiers added together. For example, with Rapid Fire Aimed Shot Crits will be our big damaging ability, a normal Aimed Shot will look like this:
Damage = 4.20*(WD+2.8*RAP/3.5)
Assuming we have about 30% crit (we're in dungeon blues, remember), we can just multiply our total result by 1.3 and we'll have the average value of an Aimed Shot. With 3833 AP, and a 630 weapon that has 901.5 WD, that works out to 21,666.7. During Rapid Fire we add 60% crit chance, so our 1.3 multiplier becomes 1.9, which puts our average value at 31,666.7.
While the DSC (I got tired of typing it's name out) buff is up, we'll add the AP gained from the Agility to like this:
Damage = 4.20*(WD+2.8*(RAP+"DSC AP")/3.5)
Crit will work the same way, so with DSC's buff, but no Careful Aim/Rapid Fire, we'll have an average Aimed Shot be worth 29,676.5, or with Careful Aim, 43,373.3.
To compare the value of stacking vs. not stacking the two buffs, we can simply look at the sum of DPS gain from using LSD without Rapid Fire (8009.8 damage per Aimed Shot) and the gain from using Rapid Fire without LSD (10,000 damage per Aimed Shot), and compare that to the gain from using both together (21706.7 damage per Aimed Shot). Because 21,706.7 is greater than 18009.8, it's clear that stacking the two buffs together is going to be superior to using them separately. And, that doesn't even include the added benefit of having shorter cast times on Aimed Shot due to the Haste aspect of the buff.
Stacking Rapid Fire with your trinkets (and when possible with your potion) will provide the greatest increase to your DPS of all the things I'm going to write about today. However, there are certainly other smaller things we can do to increase DPS. These will all change depending on what talents you take, and to some extent, what type of fight you're in (AoE, Cleave, Single Target, etc.).
Thrill of the Hunt
If you're using the Thrill of the Hunt talent, you'll want to save your Rapid Fire until you have a full three stacks of TotH. This is really the primary reason that Thrill of the Hunt, even after all the nerfs it has received since MoP, is still such a good talent. If you save your Rapid Fire for when you have three stacks of TotH, you can quickly cast three Aimed Shots in a row for the low net cost of about 10 focus (30 focus each, plus the return of 20 per crit (and they all should crit) and your base focus regen). And even though these Aimed Shots will have a very low net focus cost, they still have the chance of re-proc'ing TotH as though they cost 30 focus.
Of course, the point of this is, the less focus you spend, the less time you'll have to waste casting Steady Shot or Focusing Shot, the more time you can spend casting Aimed Shots.
Steady Focus can get us into a little bit of trouble, because to keep the buff up, we'll be casting double Steady Shots, and during Rapid Fire, you don't want to waste your time casting Steady Shots instead of Aimed Shots. The easiest way to deal with this problem is to take Focusing Shot, in which case you'll only have to cast it once to get the Steady Focus buff, and it will only cost you the cast time of one Aimed Shot (while giving you considerably more focus than two Steady Shots). However, with the current tuning of DPS, many hunters will prefer to take Lone Wolf instead of Focusing Shots, so it's worth considering how to use this ability while casting double Steady Shots.
To get the most out of this talent, we'll always want to cast our double Steady Shots immediately before casting Rapid Fire. We'll be wanting to pool focus for Rapid Fire anyway so we have plenty to cast Aimed Shots, so this shouldn't change what you're doing much, and will give you 10 seconds of increased focus regen without having to worry about the buff. If you had enough focus, you could simply let the buff fall off and finish the duration of Rapid Fire simply spamming Aimed Shots (and Chim Shots), however, that doesn't look very likely. With the high cost of Aimed Shots without TotH, you'll need to use Steady Shots during Rapid Fire. This will depend on what your haste level is, but in general it's going to be decision you make as you play. If there's any way to get away with only using one Steady Shot during Rapid Fire, then I prefer to do that, letting SF fall off. However, if there is any chance I'll have to use a second Steady Shot (which is pretty much always), then I'll do a double Steady Shot starting around the 6 or 7 seconds mark (from when I first hit rapid fire).
Lining Up Chim Shots
Until we get the set bonuses, Chimeara Shot will not be benefiting at all from using it during Rapid Fire. However, the average damage of Chim Shot (even when compared to the =60% crit chance of an Aimed Shot during Rapid Fire) will be giving you more damage than Aimed Shots, so it will remain at the top of your shot priority.
If we didn't have an on-use trinket to use with Rapid Fire, we would generally want to use Chim Shot immediately before Rapid Fire, so that we only have to use once during Rapid Fire without delaying it or reducing our total number of Chim Shots. With the trinket, however, we'll want to make sure we get as many Chim Shots as possible during the the trinket's buff.
In order to get three Chim Shots into the 20 sec buff, you'll have to either, after hitting your Rapid Fire macro, use Chim Shot first, or cast one Aimed Shot and then a Chim Shot. This will result in having two Chim Shots during Rapid Fire (which you'll want anyway once you get the 4-piece set bonus), so, for those who are really trying to squeeze out every last bit of DPS they can, you can leave your trinket and Rapid Fire not macro'ed, and cast:
Rapid Fire/Aimed Shot,
Rapid Fire/Aimed Shot
This method will allow you to get three Chim Shots during the duration of your on-use trinket, while only having one Chim Shot interrupting your Aimed Shot spam during Rapid Fire.
It's worth noting again that once you do have your 4-piece set bonus (which should happen a good deal faster than normal, with normal and heroic having completely separate lock outs from each other, and from mythic) you'll want to make sure you cast at least 2 Chim Shots during Rapid Fire (to take advantage of the increased crit damage). Some top hunters have suggested that we should save Chim Shot for the very last GCD of Rapid Fire with the 4p, but I don't have enough data yet to say if that's actually ideal or not. I can say that from playing with it on the beta, you'll see some insane 120k+ chim shot crits if you use that method, which feels pretty damn good.
One question I've had from a couple different people was regarding the use of Focusing Shot. The question goes something like this: "If we're taking Focusing Shot, if we're using FS right before Rapid Fire so that we have plenty of focus during RF, wouldn't it be better to use RF right before FS so that it has a shorter cast time?"
I believe (though I haven't really checked) that if we still had MoP's Rapid Fire mechanics, that would be true. However, with the addition of Careful Aim, we're going to see more damage by waiting out the normal cast time of Focusing Shot, then after casting RF spamming Aimed Shots.
To think about it, we can compare the amount of time we save by using FS during RF to the amount of damage an Aimed Shot would have done in the same amount of time. And we don't actually have to look at the real value of Aimed Shot to know which is going to be better, because the amount of time saved by using FS during RF will always be a fraction of the cast time of an Aimed Shot, and the amount of time we spent during RF casting FS will always be exactly equal to the cast time of one Aimed Shot. Since 1 will always be greater than a fraction of one, we know that it will always be better to cast Focusing Shot before, not after RF.