All credits to Icefrog for his amazing work on DotA.
DotA 6.63 has a very long changelog that can be seen here
http://www.playdota.com/changelogs/6.63
DotA is set up as an epic, ten player battle that takes place over the course of about an hour-long game. There are ten players at a time, split into two teams of five. Each player takes control of one hero, and the teams fight it out across the battlefield with the help of computer controlled units and structures until one side destroys their opponents' Ancient. The Ancients are heavily defended structures situated in the middle of each base.