The Majors have been on the horizon for the Dota 2 [official site] pro scene for a while now. They're a series of big tournaments spaced through the year and around the globe culminating in The International. But Valve were reluctant to go into further detail until this year's International was done and dusted - i.e. now.
The bit I'm most interested in is the restrictions this places on teams with regard to kicking players or reworking the lineup but first here's some basic detail:
The first Major will be a European affair taking place in November. Europe's going to be quite the place to be for MOBA eSports fans this Autumn it seems as October's going to be all about Riot taking League of Legends' World Championships hither and yon on the continent.
Open qualifiers for November's event will take place 6-9 October and two teams from each region will be added to the regional qualifiers lineup (that'll be taking place October 10-13th).
As you might expect, some of the top teams will skip the auditions process that is the qualifiers and receive a direct invite to the Major (I hope it has a catchier name than that), while other teams will skip the open qualifier stage and get a direct invite to regionals. All of that will be revealed on October 5th.
With that out of the way let's have a look at the roster stuff.
Through the registration system admins issue invitations to join a team to players and substitutes. By accepting the invite that player is then locked to the team until just before the next official trade period. In this case that would be just after the conclusion of the first Major.
"While a player is locked to a team, the team cannot kick the player, and the player cannot leave the team."
If you need to make a change after the rosters are locked down (the official end date for this current trade period is 12am PDT on September 5th) you can do so but it means the team forfeits the ability to get a direct invite to Majors of the regional qualifiers. The same doesn't apply when it comes to sponsorship, though. You can switch organisations or sponsors as much as you like, you just have to stay together as a set of players.
It's a move which fits with Valve's philosophy for The International, which is that they invite rosters of individuals who they have watched prove themselves rather than inviting the team name. I'm also not sure how the primary/sub thing works. You're allowed to switch a primary for a sub if both players agree but the primaries are the ones who get invited to Majors so if you switch after that invite or if you need to switch during the event does that mean you can't?
You can have a look at the list of noteworthy confirmations here. Apparently Fear is yet to lock in to Evil Geniuses but Arteezy and Universe signed up within a minute of each other so I am now picturing them doing so while sitting together in a room eating ice cream. Except Artour ate his too fast and got a headache. It was too brainfreezy for Arteezy.