Cataclysm is on the horizon but Blizzard is making it look ever-closer with the teasers they've already given out. This week, however, the previews have stepped up a gear with the first tidbits of class changes. We already have previews for warlocks, priests, shamans and warriors, with the other classes coming up in the next few days.

The most recent preview, released today, announced a significant nerf to Mortal Strike. The ability, which has been a staple of warrior PvP since the game's release, will be reduced to a 20% healing debuff. However, Blizzard made sure to point out that other similar effects will also be brought into line (presumably Wound Poison and Aimed Shot). On top of that, "heals cast by players in Cataclysm will be a lower number relative to players' health."

The beta for Cataclysm will also give Heroic Leap another chance to make its way into the game with some interesting mechanics. From the original post:



Another fundamental ability from the WoTLK beta that will be tested for Cataclysm is Shadow Word: Barrier. The discarded spell looks to be making a return and was described in the preview as being "like a group Power Word: Shield." Similarly, warlocks will finally get their long-awaited soul shard overhaul.

The complete list of changes, given that there are already four class previews, is far too long to post here. But to see them all, including shamans, you can go to MMO-Champion.