The evolution of Defense of the Ancients is now freely available, as Riot Games opens up the beta for League of Legends in advance of its October 27th "pre-season" launch.
Why "pre-season" you ask? The competitive online strategy game uses a seasons model in order to keep gameplay fresh for everyone involved. October 27th sees the start of its pre-season, a period in which players can form teams, learn the game, and formulate strategies in advance of season one, which kicks off in early 2010. The model also allows Riot to cycle content, meaning the set of Champions you have at your disposal and the maps you play on can change with each season, keeping the game fresh and the competition on their toes.
Riot has just opened up the beta for the game, allowing anyone interested to sign up and participate for free, holding on to their accounts once the game launches. The closed beta has been running for awhile, so you're late to the game, but every extra day helps. You've got five. Go play.