This seems to be a lot more challenging than you would think. You can't just change the CD fields on an item and have it work, because it doesn't.
The objective is to put a warp on a (lets say 10 second) cast; and have their be no cooldown. The hearth is a viable option but it has a 60 minute CD; and I searched but couldn't find guides on how to lower it. Not to mention you can't control the destination too well.
Second option is an in combat check. I would much rather prefer timed cast because in combat can often bug. But either way I've tried both ways and have had little luck.
I've tried several different flags and item classes, maybe I overlooked something?