The dungeon features three floors, each of which ends in a boss fight, and there's a bit of randomization in the mix, too. Each time your party enters a particular room, you'll need to fight a miniboss. Defeating him triggers a random door which leads deeper into the dungeon level and eventually to the floor boss.
With a new dungeon comes new drops and new equipment. Steparu says that farming The Spiral Labyrinth will likely be necessary to compete in the game's upcoming PvP content. Have a look at the dungeon's first minotaur boss after the break, then head to the source link for several more gameplay videos and analysis.