complete the regular arenas in campain mode to play the bonus arena, the keeper.
you can then select the reaper and mistress charecters in multiplayer mode
During gameplay, hold L1 + R2 + Select and press X, O, Square, Triangle, X, O, Square, Triangle. This enables you to automatically win.
Since the game does not have a pause option in multi-player mode, simply press Start, then highlight "Quit" and press X. Your game will be paused, but it will not quit unless you select "Yes". To resume the game, select "No".