The left hall-that seems darker then usually

You precede to the left hallway, keeping your guard as you do. As you do, you notice the number of torches that have been giving you light so far, seem to be littling as you walk, So much so, you had the take the last torch you in the hall to continue on.

After a good few seconds of walking later, you find that hallways design changed. The walls, seem to have holes in them, and the floor patterns had some engravings now. You recognize it. It's a classic style dart room trap.

You wave your torch around on the floor for any wires, or something to set off the trap. After your examination, you find that the stone plates are the triggers, and if press downwards, a iron ball could shoot out of the holes inside the walls, or right infront of you.

You know it's trap, and due to you searching around the hall. You even managed to find engraves on the roof to help solve it as well. So...