Player's Handbook[]
The character is trained as a builder of both great and small things. Engineers can prepare plans for everything from simple machines (catapults, river locks, grist mills) to large buildings (fortresses, dams). A proficiency check is required only when designing something particularly complicated or unusual. An engineer must still find talented workmen to carry out his plan, but he is trained to supervise and manage their work.
An engineer is also familiar with the principles of siegecraft and can detect flaws in the defenses of a castle or similar construction. He knows how to construct and use siege weapons and machines, such as catapults, rams, and screws.
Player's Option: Skills & Powers[]
Engineering: This proficiency is required for the design and construction of objects and installations of all sizes. Note that carpentry, stonemasonry, blacksmithing, or other proficiencies also might be necessary for the actual building. Characters can design and supervise the building of houses, boats, small bridges, palisades, and towers—of up to about 30 feet high without proficiency checks.
Characters with this skill can try to design large bridges, fortresses, ships, war machines, locks and dams, and other more complicated projects. Plans for these types of objects generally require at least a week—more if an exceptionally large project is being attempted. Complicated tasks require successful proficiency checks before a workable design can be made. If a check fails on a roll of less than 20, however, the engineer will be aware of the failure and can seek to create a new design—go back to the drawing board, so to speak. On a roll of 20, the design is flawed but the danger will not be discovered until after the object is built.