Warden Planet is the term given to Imperial worlds of the Cordon Impenetra, that border the Ork Empire of Octarius. It was created by the Inquisitor Nashir Sahansun, after the Octarius War began and he ordered these worlds to be fortified against incursions by Tyranids and Orks.
Warden Planets are tasked with warning the Imperium against any Xenos expansions from the Octarian Empire. They also serve as bases from where strike forces could be launched into the Empire, in order to prevent the Orks or Tyranids from having too much of an advantage.
- 1: Warhammer 40,000: Kill Team Core Manual (3rd Edition) Octarius Book, pg. 6 — War Zone: Octarius