I have this macro'd on my mages & pally, but don't use it very often. At the moment it seems to only work when I'm outdoors. Usually if there is a ceiling over my head the mages just show their green targeting circle on the mouse cursors (think it has to do with the pinging indicatting a out-of-range area like too far above/below the mages). I mainly just use it for 'shows' outside cities and rarely in combat. If this ever gets troubleshooted, I might re-spec a few points in the Blizzard talent for movement impairing - until then its just a toy inch: