finish levels 1 to 10 on what ever setting you want
you only need to beat the last part of the game to unlock it
once you hit 11, need to turn the game to nightmare mode before you start the chapter
the game will let you lower the difficulty during a chapter but you cant raise it.
took me 3 trys to beat it
had to change gear and equipped actions almost every fight
used the Passive Abilities
-The Axe
-Rabbit Foot
-Lucky Core
Active Abilities
-Rockfall
-The Castle
-Glowing Eyes
if your still stuck go back to the 1st chapter and play it on easy to build up wild cards