Fall of Prospero

The Fall of Prospero, also referred to as the Scouring of Prospero or the Burning of Prospero, was the name of the sanctioned reprisal against the Thousand Sons Legion homeworld by the Space Wolves Legion and elements of the Adeptus Custodes and Sisters of Silence, for their flagrant violation of the Emperor's edicts of the Council of Nikaea.

The Red Sorcerers of Prospero
Of all of the Primarchs, the genetically-engineered sons of the Emperor of Mankind whom led the vast Legions of Space Marines of old, Magnus the Red was probably the most powerful psyker of all the Primarchs. He had been raised on the Planet of Sorcerers, Prospero. This unusual human world was a veritable paradise which embraced the psychic mutations amongst its population. These psykers were not outcast by their fellow Prosperines but were instead embraced as their world's leaders. When the nascent Primarch was found in his pod that had fallen from the heavens, he became a ward of the psychic scholars and leaders of Prospero, and quickly gained the same powers. He soon surpassed his primary master in the psychic arts and became the planet’s preeminent sorcerer and leader of the ruling Commune of Prospero. Elevated to be the rightful leader of Prospero, he unified its sometimes squabbling Cults of Sorcerers, and set towards rebuilding Prospero into a centre of knowledge and the occult.

When the Emperor was reunited with his long lost son, he cautioned Magnus about the dangers of sorcery and the nature of the warp. The Emperor knew that Magnus was very powerful psyker and possessed an unquenchable thirst for knowledge. Feeling that is was far more dangerous for his son to remain ignorant of the secrets of the Immaterium and the ancient, dark intelligence which resided there, the Emperor showed Magnus the truth. Feigning shock and horror at the Emperor's revelations, Magnus agreed to renounce sorcery and to lead his people away from the study of the occult, but he secretly dismissed his father's warnings. For Magnus had already peered into the Warp with his one great eye and had become obsessed with the potential promise of power.