Basically if you are casting one spell but spamming the button of another spell at the same time. When you get stunned, cced, or interrupted the second spell will cast even tho your cced!
Basically if Im casting Frostbolt then get cyclone while im also spamming my polymorph key.. The Frostbolt will stop but the poly will go off while im still cced.
Here is the vid: [ame="http://www.youtube.com/watch?v=BjkS-K2kh34"]YouTube- MMOWNED - wootpeng[/ame]
EDIT: I figured out why its not 100% it has nothing to do with latency.. It depends on whether or not your off GCD yet. So this will only work after your cast has gone through 1 - 1.5 secs (depending on haste)