At the end of this post is both an entertaining and hilarious video. The level of play is questionable to say the least and there is an obvious skill separation between the two teams, but the video offers useful instruction.
The Legion team picks five heroes, Jeraziah, Demented Shaman, Accursed, Slither, and Wildsoul. The first three heroes have something important in common; the ability to heal and prevent death. That allows for a more effective push by preventing death (obviously) as well as freeing heroes from having to go back to the well to heal. In addition, their healing ability allows the Legion team to pull off an early Kongor kill with the help of Wildsoul and Slither. From there, with extra experience and a token, the Legion team simply storms the middle lane and wins in a swift and violent fashion. To further their ability to push, the Legion team adds a mana ring, supplying their all-important healers with a virtual infinite supply of mana, especially because of the low mana pools in play at lower levels.
Here is the movie, enjoy.