Legio Custodes

Not an order but an assembly of individually crafted warriors under Captain-General Constantin Valdor, whose bodyguards are the Ares Guard. Their “Blood Games” — constant training invasions — tested the security of the Palace, and their armament (Guardian Spears, Sentinel Blades, anti-grav machines) was the finest in the Imperium. The main front of the Custodes became the War Within the Webway beneath Terra, where together with the Sisters of Silence and the loyalist Mechanicum they held the nodes of the Webway against daemons after Magnus’s breach; there the tribunes Kadai Vilaccan and Jasaric fell, and the legion was reduced by roughly nine tenths. Tribune Ra Endymion of the Hykanatoi remained to carry the war on to the end; the surviving Custodes defended the Palace at the Siege of Terra and stood guard at the Golden Throne.

They suffered ~90% losses in the War Within the Webway; the survivors stood to the end at the Siege of Terra and guarded the Golden Throne after the Emperor’s internment.