Botmaster5 wrote:CoA is not mana efficient.
What are you talking about? CoA is a lock's most mana efficient spell. I suppose maybe you're referring to it not dealing much damage, and its damage increasing as it reaches the end of its duration, but if you mean that, then LITERALY EVERY DOT is not mana efficient. If there's not enough time for the dot to tick, its not worth casting the spell.
However, as you point out, CoA suffers especially bad, as it does very little damage for the first 12-15 seconds (I cannot recall its exact damage increments atm). However, it costs so little mana in comparison to immolate, corruption, and shadowbolt, that its mana efficiency should not be your concern. What your concern should be is "is it worth spending a gcd on this." Even while grinding solo, often times the mob dies well before 12-15 seconds (or at that point) and as such its really not worth using unless you're pulling more than one mob at a time.
As for CoS rank 1 (and really rank 2), you get 8% more shadow damage dealt. That means for every 12.5 shadowbolts you cast, you've effectively done an additonal shadowbolt worth of damage. In otherwords the GCD of CoS (assuming you do not have any points into bane) is worth using when you have cast 6.25 shadow bolts as seen by the equation: (GCD for CoS/SB cast time * x number of casts) =.08 * x number of shadowbolts or (1.5/3x)=.08x. Notice that when you reduce the cast time, the number of shadowbolts actually gets worse: (1.5/2.5x)=.08x means it takes 7.5 shadowbolts for CoS to be worth the GCD cast. Now, I only included shadowbolt in the rotation. When you factor in that immolate does not benefit from CoS and the fact that corruption's cast time is low as well, its easy to see that CoS is not worth it unless the fight lasts a considerable amount of time.
Now the question, whether CoS is worth it or not, all depends on the ranks of the spells you have and how much damage they're doing. I'll answer this specific question when I get home, as it includes more arithmetic than I have time for at the moment. However, hopefully I've given you an idea of the benefit of CoS, and I seriously doubt that it will ever be worth it (over using CoA) when you're the only shadow damage source in the party. But, remember, CoS does have the added caveat of reducing shadow resistance, so if you're noticing that you're getting an unusual amount of partial resists, it is probably beneficial to apply it (as partial resists are a SIGNIFICANT decrease to damage).
Posted: Fri Jun 19, 2015 1:52 am