Six combo points
Our two-piece bonus indicates that it will enhance the duration of our finishing moves by one combo point. If you use Slice and Dice with two combo points, it will last as if you had used three combo points. If you use SnD with five combo points, it will scale as if you had used six combo points. Because all of our combo point scaling is uniform, it's easy to figure out the net effect of this set bonus. Rogues typically try to use only five-point finishers, since it guarantees a Relentless Strikes proc for 25 energy.
Assuming a five-point finisher, Slice and Dice will last for 42 seconds (previously 35), Envenom's buff will last for 7 seconds (previously 6), and Rupture will last for 28 seconds (previously 24). Kidney Shot and Recuperate are also affected, but since these are typically only used in PvP, they don't affect our DPS in any way. Notable exceptions to the set bonus finishers are Crimson Tempest, which has a fixed duration, and Eviscerate, which is the only finisher without a duration of any kind.
Breaking down each finisher
Increasing the duration of our Envenom buff directly improves an assassination rogue's damage. Assassination rogues will see extra Deadly Poison procs with the two-piece bonus active, but the exact amount is difficult to fit into a simple model. Lengthening the Slice and Dice buff will allow combat and subtlety rogues to sneak in more Eviscerates between refreshing it. The SnD bonus doesn't affect assassination rogues at all, since they can already refresh SnD for free with Cut to the Chase. Rupture will be attractive to combat rogues now, as it was already competitive with and will be better than Eviscerate with the bonus. Rupture is the only finisher affected by the bonus that influences all three specs.
Increasing the durations of Slice and Dice and Rupture isn't a DPS boost by itself. Slice and Dice still increases our attack speed by the same amount, and Rupture still does the same amount of damage per tick. The secret is that longer durations on SnD and Rupture allow us to use fewer combo points to keep them active at all times, so we have more combo points to spend on other damaging finishers. Over a typical 5-minute encounter, we'll have to spend about 15 fewer combo points each on SnD and Rupture, for a bonus of 6 Eviscerates per fight. It adds up to a 2-3% boost for both combat and subtlety rogues overall.
Less maintenance, more damage
One of the unseen perks of the two-piece bonus is that it lets us focus more on our damaging finishers and less on our maintenance finishers. We'll be able to see more Envenoms and Eviscerates pop up on our screen, which is always a good feeling. With the buffs to Envenom, Sanguinary Vein, and Vitality, rogues will be dealing more damage overall and a larger percentage of that damage will be active, not passive. I think it's a dramatic improvement over the "Sinister Strike does 10% more damage" model that never really changed our rotation or the feel of the class.
Cooldown stacking and Shadow Blades
Cooldown stacking is a time-honored tradition in World of Warcraft. Syncing up Bloodlust with potions and personal cooldowns is what playing a DPS class is all about. The math is simple: stacking cooldowns will always yield more damage than spreading them out. We all love seeing that brittle yellow bar rise to the top of the Recount meter. Rogues have been stacking cooldowns since we've had cooldowns to stack.
Shadow Blades, the major spec-agnostic rogue CD, is best when synced with our other cooldowns. In fact, the Adrenaline Rush/SB combo for combat rogues makes up a scary percent of their damage, to the tune of 15-20% overall. Shadow Blades also works with assassination's Vendetta and subtlety's Shadow Dance. Always stack SB with another CD if possible.
The four-piece bonus reduces the energy cost of our abilities during Shadow Blades, which further pushes into the stacking mentality. I can't wait to unleash a massive Shadow Dance combo while under the effects of the enhanced Shadow Blades with our four-piece bonus. The amount of burst we'll be capable of putting out will be amazing. The only downside is that SB is a 3-minute cooldown, but the wait is worth it.
Combat's carpal tunnel problem
The issue is that combat rogues are already flush with energy during Adrenaline Rush, which is why Blizzard introduced the Glyph of Adrenaline Rush. The new four-piece bonus, when synced with Adrenaline Rush, would result in combat rogues being completely unable to burn all their energy fast enough. Blizzard's first suggestion was to split up AR and SB, which is a very bad idea. In fact, the four-piece bonus actually could've been a DPS loss if it caused us to unsync SB and AR, which are so potent together.
To quell the issue, the four-piece bonus will now also reduce combat's global cooldown even further. When coupled with the Glyph of Adrenaline Rush, combat rogues can spam their abilities twice per second. The number of actions we'll be able to unleash in unparalleled by any other class, which typically have a minimum GCD of 1 second. While I'm glad the set bonus will still work for combat, I'm not happy about the direction that the spec is going. I'm not looking forward to having to frantically smash my keyboard in order to get the full effect out of my set bonus and 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.