The reason I quit playing 4x pallies and 1x DK was because 1 frost mage could lock me down and sometimes even kill my entire team. If nothing else grief the hell out of me.

With shamans, they aren't a problem. Just put pressure on the mages when they are easy to target, and watch out for their AOEs. Don't chase them down, focus on the easy targets to relive some pressure. Once they blow their ice block they are a lot less aggressive.

You have to put pressure on the mage though when you can, otherwise they can really go to town.

Seems like most mages are frost now, which is just a pain with all their frost novas.