whenever any of my guys get hex'd I just spam interrupts and aoe's on my main or dispell as quickly as possible (decursive hotkey on each) if I can. realistically though, before every pull I think might be difficult I set a focus for each of my mages in case this happens, then I hit my stop follow and sheep macro. While this might suck if you got the mob to less than 50% its better than wiping. Also, if you hit Arcane Missiles for the mages fast enough after the sheep they don't gain any health and auto turn to follow the target.