Welcome to the world of GCD clipping, a place where Balance Druids have lived for a long time now.
Originally Posted by CoolNitro
When a spell's cast time drops below the GCD minimum of 1 second, while the spell only takes it's cast time to cast, you have to wait the remaining duration of the GCD before you can begin your next cast. My personal record to date was a 0.464 second Wrath cast time back in Burning Crusade (good ole Quag's Eye).
When you cast a spell that has a 0.75 second cast time. You complete the spell after 0.75 seconds, however have to wait the remainder of your GCD before you can cast your next spell. Assuming your GCD was at the lower limit of 1 second, this means you have to wait 0.25 seconds before casting your next spell ("Spell Not Ready Yet" error). If your latency is 100ms, the actual time it would take for you to spam this spell is 1.1 seconds per cast.
If your GCD timer is off, you likely assigned it to the wrong ability.
All abilities that have a cast time are on the GCD, always. It's just when that cast time is longer than the GCD you don't notice.
"In anything, if you want to go from just a beginner to a pro, you need a montage." /w TankSpot WTB Montage for Raiders.