Builders can be used to accomplish multiple types of tasks. They are mostly used to build new buildings and upgrade them. They can also repair damaged buildings, such as walls after an attack by monsters, can cut down trees and can build teleportation portals on destroyed portals. Builders will also man and operate catapults and ballista towers, ensuring that they work properly to eliminate large groups of enemies at a time.
When the Monarch assigns multiple tasks, builders will act according to various priorities. For example, a task farther from the Town Center is usually given a higher priority and repair jobs have low priority. The builders do not seem to keep task lists and so jobs do not seem to be prioritized according to when they were ordered.
Most tasks can be done by two builders instead of one, with the second builder rushing to help the first, although this has low priority if there is another task to do. Idle builders will not rush to a task if two of them are working there or heading there already.
When a builder is assigned a job outside the kingdom's outer walls, they will attempt to fulfill the Monarch's orders regardless of whether it is day or night (and so they do run outside of the walls at night), but builders will ignore job assignments that are close to black Greed portals, even if the portals are inactive. When builders completes a job outside the outer walls, they will idle out there if it is day, unless they are given other tasks to do. If it is night, they will walk (in Classic) or run (in New Lands and Two Crowns) back until they are inside the borders again.
Builders can hold only up to two coins. In Classic any extra coins picked up by builders are lost (eg: if the builder is seen to pick up four coins, the Monarch will only be given two when collecting from the builder). In New Lands additional coins are not picked up by the builder after the limit is already reached.