Ticket sales for Dota 2's The International go on sale tomorrow, Tuesday, June 12th. The first batch of tickets will be available starting at 9:00 AM PDT/17:00 GMT via the Dota 2 store for $49.99.
Tickets will grant you access to all three days of The International. The ticket itself has no value unless you attend the event, so don't try for one of those get rich quick schemes either.
Valve expects tickets to sell out quickly. If you don't get a ticket this time, Valve will be releasing an additional batch each day at the same time concluding Saturday, June 16th.
After purchase, the ticket will be located in your Dota 2 inventory and can be traded like any other Dota 2 item. Upon use the item will be consumed and your Steam account will be flagged as attending. Your confirmation and access pass required to enter the event will be emailed to you at a later date so make sure your Steam contact info is up to date.
There is also a limited amount of first come, first served seating for those with PAX Prime passes.
