The Emperor Wept (Warhammer 40,000)

The Imperium has decreed that the world of Carnage is to die, to test a new strain of the monstrous Life-Eater virus. Space Marines of the Doom Warriors descend upon the world to deliver its end. But when something unforeseen occurs and the world survives the virus, a single adept of the Magos Biologis - Heironym Rottle - holds the key to the mystery.