Every night time stars fall from the sky. Collecting ten of these lets you increase your maximum mana. On normal terrain this can take a long time and can be a risky proposition in pitch-darkness. By creating a Sky Bridge (by making a ladder about a hundred or so blocks in the air and then laying down stone or dirt in a straight line) you can create a long stretch of easily-traversable land for the stars to land on. With a speed-increasing item such as Hermes Boots or Necro Armor equipped you can travel the length of your bridge collecting stars relatively uninhibited. Zombies will still spawn on the bridge and you might get the occasional harpy or demon eye, but you won't have to contend with rough terrain, chasms, water or anything that spawns from the corruption.
