Attacking players from there profile has now been added to the game. The big red attack button should now be functional for everyone! Previously only players within a 6 level range of your current level were available in the fight arena. Now you can simply attack any player regardless of level outside of the fight arena but it comes with some risks. If you wish to mitigate all risks then stick to the fight arena otherwise you could potentially break any equipped weapons/armors, lose large amounts of money/gold and even potentially lose some of your hard earned stats.