So I started to play around with channeled spells, and noticed that if you put Warpath on your bar 2x.
You may channel 1 of the Warpath skills (hold the button down forever)
You may cast the other (un-interrupted) for double damage every global cooldown. (press secondary Warpath every time it is available. To see the bursting damage while maintaining a Warpath channel)
I am curious to test this with other spells. I am heading over to try my mages Elemental nova, see if I can channel + cast.
You cannot have a 3rd Warpath, to triple or go further, subsequent Warpath abilities share the GCD. But the Channeled one, remains grey (in use) the whole time, while additional warpaths abide by the GCD.
I imagine this is not intended, and I am positive I will find the same interaction on other Channeled skills. Have some fun before they fix at least.