At a certain point in Darksiders Genesis, you will have to enter a dungeon to continue the story. The entrance to the dungeon can be spotted is in The Furnace. You will spot a level on the left column. Interacting with the level will open up a passage that you can use to reach the upper floor. You should quickly jump off the lever and on to the opened wall section. Hurry because spikes will come out and kill you. You will find the dungeon passage on the upper floor. Getting to this area is easier if you playing with a friend. There are two levers you need to activate, your partner can do the other one but if you are playing alone use the bomb growths to trigger the other lever.