I've played combat for a long time on Cataclysm now, and what i can say is that you must make very quick decisions due to the sudden energy bursts that you get. You may be around 85 energy and planning ahead, but suddenly a Combat Potency Proc makes you waste energy. On this regard, it's like the hunter's focus bar atm: if you get low on energy it can be complicated, but acumulating too much is going to be a waste. Managing your energy as well as the Bandit's Guile buff are important matters. Saddly a DK on a random heroic said assassination was better atm for DPS, and my 6.7k output at gear lvl 331 explains that, i think. (P.S.: i was using Expose Armor at that time, since we had no sunder classes on the run)

Also, regarding Killing spree, i'd advise to use it when you're at the start of combat, building combo points for Slice and Dice. You may think that it would be a waste due not to use it on the Bandit Guile's full buff time, but think on this side: the best CD to use during the first Bandit's Gule time would be Adrenaline Rush, and the massive number of finish moves during it, and also between the first and the second Bandit's Guile would lower the Killing Spree CD enough to be used on the second Bandit's Guile due to the Restless Blades talent.

These were my opinions on the thought of this matter. I hope they helped. Combat is the aspect of the rogue i like the most, and i plan to improve it further.

Reply