The Dota 2 blog has updated again today, detailing what is in the upcoming patch, which we also now know will be tomorrow. Skeleton King is becoming the Wraith King and will be the focus of what seems to be a horde-mode variant, which involves protecting the Wraith King from enemies until he can be "reborn in a form more imperishable than bone." Naturally, there will be items gained from playing, which involves getting Phantom Fragments and redeeming them for reliquaries.
Also included in tomorrow's update will be Legion Commander, a new Hero to Dota 2, a "newly crafted path for beginners," ranked matchmaking, and of course new hats. Oh! And the 6.79c gameplay changes, which include an increase to the cost of Hand of Midas, Slark and Huskar being added to Captain's Mode, and giving people an abandonment when a party member abandons a game. If I were you I'd make sure your Internet is pretty steady before playing with buddies from now on.
You can check out all the new changes in the blog post.