I have a question. In the OPs opening statement he tried to showcase the actual "cost" of an instant cast by subtracting the GCD from the cast time. I think he did 2.6s - 2.31s getting a positive 0.29s. But isn't that the reverse of the logic. I would think you'd start with the GCD first and subtract the cast time. Because with the you'd get 2.31s - 2.6s = -0.29s indicating that you've wasted 0.29s before you can next attack, if the skill is hard casted. This works with all of the spells/skills that have cast times. Its recast - cast to show you how much time you gain or lose to use another skill OGCD or GCD.if I have an instant cast Fire spell that's basically 2.31s - 0s = 2.31s, giving me that time to use an oGCD skill in its place or move as needed.