Most of what’s actually in the beta won’t come as a shock since it’s been shown in videos already. Expect the opening mission and cinematics, a new mode for Crucible, The Inverted Spire Vex stronghold, matchmaking, grouping, and the new subclasses: “The new fighting style for each Class will be at the ready. Choose from the Dawnblade Warlock, Arcstrider Hunter, or Sentinel Titan.” There’s a stress test on July 23rd if you’re inclined to go help break the server.
Clan support and character progression won’t be in their final states, and of course, “Nothing we do in the Beta will carry over to the final version of the game on September 6” — except for your beta emblem.
Source: Official site, official blog