It's a simple, "fun" game you can watch in downtime during your raid, while waiting for a queue, or just sitting around doing nothing.
You make your little dude @ http://mybrute.com/ and make sure you put a password on it.
Then you just do your daily fights. It's entertaining to watch when you get a high level.
You can post your brutes name in here as well to gain XP from people who fight you!