Only between levels and only before you pick up a perk. The altar gets destroyed after this and you can no longer edit your wands. But like superBlast said, there is a perk that lets you edit your wands everywhere. Well.. Thats hard to say. You get gold and stuff if you explore the levels as much as possible but chances that you get yourself killed are very high. I once rushed through the levels and encountered some kind of a boss monster. You have no chance without a proper equipment. The staffs you can purchase between the levels get more and more expensive, so I highly recommend collecting as much gold as possible. That requires you to kill as many monsters as you can and / or dig for the gold in the first 2 levels. I recommend getting stains of water and / or blood on you as often and as much as you can. Sure, you won't be able to benefit from invisibility or the stainless armor, but it prevents you from catching fire. The stains will vanish just by walking around, check the remaining percentage with your mouse on the symbols on the right. You should also carry around at least one bottle of water to clear toxic waste and clean yourself if needed. Most of the time I lose my health more from fire, acid or toxic, not so much from enemies, at least in the first levels. Later in the game the enemies will be much stronger and are the bigger problem.