With first DLC dedicated PvP arenas - Undead Match - were introduced into game.

Undead Match is accessible from bonfire in Firelink Shrine, but you need to acquire Champion's Bones and burn them on that bonfire first.

Champion's Bones are obtainable in DLC locations: either from killing Champion's Gravetender & Gravetender Greatwolf boss in [Painted World of Ariandel][1] or after completing [Lapp][2]'s quest line in Ringed City DLC but only if you don't own first DLC.


  [1]: http://darksouls3.wiki.fextralife.com/Painted+World+of+Ariandel
  [2]: http://darksouls3.wiki.fextralife.com/Lapp