Valve is developing a save feature
Team Secret's manager Matthew "Cyborgmatt" Bailey published a post on Twitter with a GitHub link. It reveals that Valve is working on a system that allows users to save a snapshot of the current match. The code can be found at the link — Dota 2 Saved Scenario.
Matthew explained the approximate working principle of the save feature. It will allow you to make a test snapshot of everything that happened on the map: teams, heroes, items, buildings, shop stocks, and entities. All this will be in a JSON file (text file designed for the structural description of the object).
Match saving is one of the most important features needed for the professional Dota 2 scene. Over the past year, there have been several matches where teams had to play outnumbered because players couldn't join back.
Previously, a similar save feature was present in the Dota 2 client. However, on September 2, 2015, the feature was removed after the release of the Dota 2 Reborn update.