There are several 'Arenas' to find, the first is in the bandit camp just outside Firestone.
If you mean can you fight your friends, yes you can, you need to enter an Arena, there are several to find, once in the Arena you can 'duel' with your friends.
Borderlands traditions tend to be mixed. Please specify WHICH borderlands you are referring to.
the creator of borderlands is Gearbox
Borderlands 2 is out now.
borderlands
Borderlands 2 was released on September 18th, 2012.
No, Kreig is an add-on character for Borderlands 2.
Borderlands - novel - was created in 1990-06.
Borderlands - novel - has 423 pages.
The ISBN of Borderlands - novel - is 978-0374308957.
It's not necessary, no.
The plot of Borderlands 2 is a continuation of the plot of Borderlands 1, you meet some old faces and learn some new things about the events of the original.