(Excuse the photo, guys. If you can't tell, that's 20 people playing Dota. And a shitty cameraphone.)
As part of the very loud, very silly All Star Match at this year's International, Valve have revealed that starting from next week custom game modes made in Dota 2 Reborn will support up to 24 players. This is a big increase from the current limit of 10, and a demonstration of what the Source 2 upgrade contributes to the game in general.
There'll be some disappointment that this took the place of a hero reveal, but there's still time. Dota 2 reborn is scheduled to launch soon after the International and will include a full toolkit for building custom multiplayer modes. It's not yet confirmed that Valve will add the custom mode used to play tonight's All Star to the Reborn Beta, but it seems likely.