New to viewing the DotA 2 Pro Scene! What should I learn before Shanghai?

Hey guys! I'm a frequenter of your long lost cousin, r/globaloffensive and I'm super into the competitive scene there. However, I've been seriously getting into Dota, and I'm thoroughly enjoying the depth and teamwork aspects. I'm looking forward to watching the Shanghai championship, but I'm not entirely filled in on the teams themselves (I watched a bit of TI2 but I'm sure standings have changed).

As an outsider looking in, what information can you give me regarding the teams and competition? Who are the underdogs? Who will stomp the rest? Are there any long-term rivalries that will be tested? Let me know in the comments, I'm excited to hear all about it! Thanks!