Engineers spend their time building things. Whether it's a structure, moat, or ancient machine, the Engineer is a niche vocation. While they don't normally go around adventuring, it does sometimes help to have one in the party when there is no one else that can solve an engineering problem. Sometimes you may send them off for a week to build a bridge or a house, other times they may come up with a catapult system to hurl giant boulders down from castle walls during a siege. If you need something built, and have the time and resources, the Engineer is your man/woman.