Construct: Certain machine-fighters — Servitors, Kataphron and Kastelan war-engines, and the Ironstrider and Sydonian walkers — carry the Construct keyword. A Construct is a mindless engine that does exactly what it is set to do until it is destroyed, and it is the target every Tech-Priest tends. A Construct may be mended by the Rites of Repair and is shielded by the Aura of the Omnissiah, but it does not rise on its own: a living maintainer must reach it and work. When the last priest falls, a downed Construct stays down — so much scrap that has not yet finished toppling over.
Codex · Adeptus Mechanicus