Battle.net is a service of the game manufacturer Blizzard Entertainment that allows its users to interact with each other, download games and participate in online games such as the popular StarCraft.
In the following screenshot you can see a fake Battle.net site looking to steal access credentials:
(click to see larger)
At first glance it seems legitimate, however when looking closely at the URL you can see that the word battle has 3 t, instead of 2 as the actual site, and is a domain with termination .com.
These types of phishing are quite common, since virtual relics have real value outside of the game, gamers are being a very attractive target of attack. A year ago in Finland something quite curious happened in relation to this, a stolen character from World of Warcraft was valued by justice at 4 thousand euros and the thief had to pay them.
On the actual site of battle.net You can find a security section with tips to avoid this type of deception, there is even a list with the official Blizzard domains and a guide to follow in case an account is hacked.
See also: Fake program to download all games from Steam.StarCraft 2, key generator that requests credentials from Gmail and battle.net.