The builder is a man who is skilled in Construction, and appears alongside his superior instructor at locations where caravans of Armadyl or Bandos may stop at. He can appear randomly at building points that have no building completed or started at the location.
When he and his superior appear, they will offer to build a building for player's factions, and ask for an opinion on what faction they should create it for. In a similar manner to a follower of sliske, players can give their support to the builders to convince them to create a building for the location. When a total of 20 players support one specific faction with them, they will instantly create a randomized building between the four choices on the node, which will become protected for 10 minutes in the same fashion as would a building completed by players.
When he is spoken to, he will simply state that he is here to work, and that players should talk to the master builder for information.
They will disappear after a total of 20 successful votes towards one faction, or when 10 minutes has passed since their spawn, whichever comes first.