i know the skill isn't released yet, but here you have the guide for it already.
to start this skill, you go to al-kharid, behind the bank you will see a boat with a captain next to it.
talk to him and say yes to go to the dungeoneering maze.
inside the maze there are npc's and closed gates, to pass these gates, you have to kill npc's till they drop a key. everytime you pass a gate, all keys will be deleted.
everytime you kill an npc, you gain dungeoneering experience. every port you get more xp.