World Engine - History: In 912.M41, the Necron Overlord of the artificial Tomb World Borsis was overthrown in a coup by an official named Heqiroth, who wished to expand its empire once more. Under this new leadership, Borsis' ancient mechanisms were slowly brought online and its inhabitants awakened from the Great Sleep for a new campaign of conquest.The massive mobile artificial Necron Tomb World of Borsis, designated the "World Engine," by Imperial military command, was attacked after it went active in the Vidar Sector in 926.M41 by task forces raised from 15 separate Chapters of the Adeptus Astartes plus multiple elements from the Imperial Navy, and even the mightiest weapons the Imperial forces could bring to bear could not harm it.Drop Pods and torpedoes could not penetrate its potent defensive shields and it was impossible to lock on to the massive vessel's interior with teleport beams. The Imperial task force tried twelve times to overwhelm it through sheer valour and firepower and was rewarded with a string of destroyed and crippled starships and millions of casualties. The World Engine destroyed a third of an entire Imperial Navy battlefleet before the Chapter Master of the Astral Knights decided to ram the hideous vessel with his Battle Barge, the Tempestus.It was only when the enormous Space Marine starship collided with the Necron construct's shields that they finally failed, allowing the Imperial forces to approach their target. A force of over 700 Astral Knights deployed from Drop Pods onto the Necron vessel's surface. For over 100 solar hours the Astral Knights fought against tens of thousands of Necron warriors and destroyed every flux generator, weapon forge and command node they came upon.Only after the Chapter had been reduced in size to the Chapter Master, Arthor Amhrad, and five Battle-Brothers did they succeed in their quest. Amhrad detonated Melta-charges that destroyed a vast Necron tomb complex at the centre of Borsis that housed many of the World Engine's command arrays. This detonation brought down the vessel's seemingly impenetrable Void Shields and also silenced the mobile Tomb World's potent weaponry. This allowed the Imperial Navy's starships to destroy the World Engine with Cyclonic Torpedoes.After the battle, as the Adeptus Mechanicus picked over the shattered remains of the destroyed World Engine in an attempt to salvage any valuable technology and rescue any survivors, the Ultramarines retrieved the twisted wreckage of the Tempestus and placed it amid the ruins of Safehold, the last planet scoured clean of all life by the World Engine. The 2nd and 4th Companies of the Blood Angels had been amongst the Astartes task forces dispatched to the Vidar Sector to assist their fellow Space Marines against the threat posed by the World Engine.After the sacrifice of the Astral Knights led to the final destruction of the World Engine, Captain Donatos Aphael of the 2nd Company proposed that an Imperial shrine be erected upon the world of Safehold in eternal memory of the Astral Knights Chapter. The shrine today consists of seven hundred and seventy-two arbalstone statues, one for every Astral Knight Battle-Brother that died stopping the World Engine.These statues stand a silent vigil within the dead heart of the ruined Tempestus. From that day forth, 2 Blood Angels of the 2nd Company, and Battle-Brothers from nearly a dozen other Chapters, are always assigned to stand guard over the memorial, which is considered a singular honour for the Astartes that fought beside them for the last time.