I'm playing a Demon Hunter, and the following scenario has happened more than once: while I roam happily slaughtering hellspawns, I find a pack of champions(melee hitting big guys) with the Vortex modifier. I throw a couple of shots, run away, get Vortex-ed in, almost dead, Vault away, another Vortex, BAM - dead. The same could partially apply to champions with the Teleport modifier, since sometimes I can find myself suddenly surrounded and pounded on, even though I have a little more breathing space against them.
Since I was thinking about getting into Hardcore mode sooner or later, is there anything I can do to avoid my doom, or am I going to suck it, curse my bad luck and reroll another character?