The two-piece is just extra energy
Your average assassination rogue picks up an extra combo point from Seal Fate on every other Mutilate. With an average of a 30% crit rate, the chance of back-to-back missed Mutilate crits is 50%. A typical encounter might see an assassination rogue unload 50 Mutilates or so, give or take a few. The two-piece bonus gives us 20 energy per Seal of Fate proc (ignore the tooltip), with essentially no wasted energy. Multiply that 20 energy by our 25 Seal Fate procs, and we'll be seeing approximately 500 extra energy during a 5-minute encounter. That's enough for several extra Mutilates and Envenoms, which is definitely nothing to sneeze at. The value of crit will rise significantly for assassination rogues.
Combat rogues have a 20% chance per Sinister Strike to generate an extra combo point, which would activate the two-piece bonus. Your average combat rogue will use approximately 150 Sinister Strikes in a 5-minute encounter, which will result in 30 procs from the two-piece bonus. That's worth 300 energy (at 10 energy per proc), which is a lot less than assassination is seeing. The other catch is that most of combat's damage doesn't come via energy, and as such, the DPE for combat is lower than assassination. Overall, the set bonus is very lackluster for combat, but not as bad as our tier 15 two-piece bonus was.
Subtlety rogues can get a Honor Among Thieves proc every 2 seconds, which should be pretty reliable in a raid. Over a 5-minute fight, that will yield 150 procs, which are worth 3 energy each, or 450 energy total. Subtlety is another energy-focused spec, and should see good results with all of that extra energy. We'll see what the final mechanics turn out to be, as there may be ways to game the stacking effect of the proc to maximize our Shadow Dance damage.
Ambush is back on the menu
I'll talk about assassination's new mastery-stacking Vendetta and all of combat's Killing Spree improvements another day. Today is all about the "buy 4 Backstabs, get a free Ambush" set bonus that answers the fundamental question that every subtlety rogue asks themselves: why can't I use my openers all the time? Subtlety has always been a spec that revolved around Stealth and openers, neither of which work well in a raid environment. Shadow Dance is a band-aid that's plastered over the gaping chasm between what openers are designed to do and the inherent limitations of Stealth as a spec-defining mechanic.
Every feature of the subtlety spec pushes rogues towards Ambush. Master of Subtlety, Find Weakness, and even our tier 1 talents all revolve around dropping some massive Ambushes on our target. Without Ambush, subtlety is a poor combat-clone that should be removed from the game (and probably replaced with a tanking spec, all things considered). The truth is that Ambush has always been the core damage dealer of a subtlety rogue, and putting a "more Ambushes" set bonus onto our tier 16 gear is exactly what the doctor ordered.
The subtlety four-piece bonus allows sub rogues to keep Find Weakness up over 80% of the time, and that's not including all of the extra damage and combo points from Ambush itself. Do you remember ArP rogues from Wrath? Do you remember how crazy-good they were? It's almost impossible to overstate how good this four-piece bonus is, at least the PTR incarnation. Currently, the four-piece set bonus for subtlety is better than all of the other subtlety two-piece and four-piece set bonuses in Mists of Pandaria -- combined.
What's more exciting than the set bonus is the implication of the mechanic itself. Blizzard is experimenting with ways to get more Ambushes in the hands of subtlety rogues. I've talked with a lot of you about subtlety's identity crisis and how crucial openers are to the spec's PvE health. If there's a way to shake up subtlety's dependence on Shadow Dance and to spice up its rotation, we might start seeing more subtlety rogues showing up to raids and applying to our guilds. One of the best things we can do is to give subtlety a shot in the Siege of Orgrimmar, to give Blizzard good data to work with.
I don't care what the final mechanic ends up being, as long as subtlety ends up using Ambush more often, and not just while wearing the tier 16 set. Four Backstabs turn into an Ambush? Ambush replaces Eviscerate for subtlety? Sub has a new finisher (with a short CD) that grants Shadow Dance for 1-5 seconds, based on combo points? Ambush turns into Blindside, via a 20% proc with each Backstab? Do whatever it takes, just let subtlety use its defining ability outside of cooldowns.
Sneak in every Wednesday for our patch 5.2 guide, a deep-dive into the world of assassination and combat rogue AoE rotations -- and of course, all the basics in our guide to a raid-ready rogue.