Heroes of the Monkey Tavern (EP)

The changes in difficulty affect the toughness of the monsters and the damage they inflict, but there's nothing a well equipped party can't handle in difficult mode (explore every level and get every weapon and item before going up a new dungeon level). After killing the last boss and finishing the game, this trophy will pop. If you haven't played the game in any of the lower difficulties, those trophies will pop along with this one.