Hereos of Newerth?
HoN is a game that is based on the WC3 mod DotA, which you might have heard of, or head a song about. The game has a really steep learning curve, and the community is really harsh against new players. BUT i'ts really fun, and it only costs $30, so run and buy it!
If you want to see how other players play, you should head over to one of the following links;
They stream on a daily basis, and it's really fun and educational watcing others play!
Visit Honcast if you want some insight on how the best players in HoN play in tournaments etc.