Freeze Mage is nearly as old as the game itself – it was played (and even nerfed) extensively before Hearthstone even came out of Beta. It wasn’t that hard to realize that combining the class’ stall potential with burn might be a good idea. However, after lots of burn cards have rotated out and Mage has lost Ice Block, the deck has only seen fringe play. Until now.
Rise of Shadows has sort of brought Freeze Mage back. It’s not very popular, but it’s definitely playable now. Depending on the build you play, you might rely a bit more on the minions pressure (including amazing Sunreaver Warmages, which can be used both as a removal and as a burn), or the combo between Archmage Antonidas and the new Ray of Frost (it’s quite easy to pull off three extra Fireballs from Antonidas in the late game now, even more if you’re on Coin). The deck is still not optimized, and I don’t think that it will become mainstream yet, but it has a chance to see some play over the next months.