Immaterium - Warp Rifts: On rare occasions, the realm of the Immaterium is able to break out into the physical universe in what is known as a Warp rift.A Warp rift is a weakening of the barrier between realspace and the Empyrean, allowing its creatures to enter the material universe. Sometimes, Warp rifts occur randomly, while other times, the Chaos Gods or mortals manufacture them.Some last mere moments, others for solar days, standard years, or even for Terran centuries. They can take many forms, often a seething whirlpool of raw psychic power, other times as a terrifying glimpse into the Realm of Chaos.They have also appeared as gates of green fire, clouds of impenetrable shadow, boiling lakes of pus, and other terrifying visions capable of driving mortals mad.These Warp rifts are usually settled by the once-mortal followers of the Ruinous Powers of Chaos, and are often the site of titanic atrocities previously unleashed in the local region of space by these forces of Chaos.A number of different factors can induce the formation of a Warp rift in realspace, including the unpredictable movements of the Warp causing a natural break into realspace; the Daemonic possession of a psychic mortal; deliberate rituals of Daemon-summoning carried out by Chaos Cultists; a breach in the barrier between realspace and the Warp caused by the psychic focus of immense suffering and death following a great war or terrible atrocity; a Warp-Drive implosion; or as a result of the unified will of the major Chaos Gods.The most well-known Warp rifts in the Milky Way Galaxy include:Eye of Terror - The Eye of Terror was created when the Aeldari inadvertently caused the creation of Slaanesh, which is now home to the Traitor Legions of the Chaos Space Marines and their other Human followers like Chaos Cultists, Traitoris Militarum and the Hereteks and Traitor Titan Legions of the Dark Mechanicum.Great Rift - The Great Rift, also known as the Cicatrix Maledictum in High Gothic, is a tear in reality and a raging, galaxy-wide Warp Storm that has essentially rent the territory of the Imperium of Man in half. The rift is known by the other sentient cultures of the galaxy by various names, including the "Crimson Path," the "Mouth of Ruin," the "Warpscar," the "Dathedian," "Gork's Grin" and a thousand other names besides. Even before the fall of Cadia, the Immaterium had been growing ever more turbulent. Travel and communication suffered increasing disturbances as the events of Abaddon the Despoiler's 13th Black Crusade unfolded in 999.M41. Eventually, the Materium could take no more, and a titanic Warp rift tore across the galaxy, spreading from the Eye of Terror to the Hadex Anomaly on the Eastern Fringe. To those on the Terran side of the rift, it is a tainted scar stretching across the sky. To those unfortunates on the far side, it is something much worse -- the very gates of Hell.Hadex Anomaly - The Hadex Anomaly is a raging Warp phenomenon that lies at the core of the Jericho Reach in the Eastern Fringe of the galaxy. Bathing countless worlds in a sickly red glow, this nebulous tear in space-time represents far more than a navigational hazard or obstruction to astropathic communication. It is a cancer upon the fabric of time and space, and entire star systems have been lost to its baleful influence. To the astronomers who study it, and the Navigators who fear it, it is known as the Hadex Anomaly. Like a monstrous heart palpitating in the void, the influence of the Hadex Anomaly expands and recedes rhythmically, absorbing and disgorging entire solar systems over the course of decades. Worlds bathed in the crimson glow of the Anomaly become saturated with its corrupting essence, while stars languish under its stygian radiance. Such stars become clotted red orbs, shedding a carmine luminescence mimicking that of the Anomaly itself. Scholars, savants, and madmen have striven to classify the anomaly in line with others of its type, such as the Eye of Terror, the Maelstrom, and the Gates of Fire, yet it continues to defy all classification. Though clearly a Warp/realspace overlap like most other similar events, the Hadex Anomaly exerts an exotic effect not just upon the physical realm but on the temporal as well. In their vain efforts to understand the Anomaly, Imperial savants have claimed it seems to "spew time" into the surrounding region, disrupting the flow of events and occasionally reordering them entirely.Heart of Darkness (near the Attila System)Hell's Gullet (in the Berillian System)The Maelstrom - The Maelstrom, with the region of Imperial space surrounding it commonly referred to as the Maelstrom Zone (also known by its ponderous Administratum designation Maelstrom Adjacent Autonomous Imperial Resource Extraction Zone Grid 004-357), is a massive and ancient Warp rift located near the galactic core in the Ultima Segmentum. This area of space is riven with Warp Storms so intense that stellar travel in the region is virtually impossible. Unlike the Eye of Terror which was created by the birth of the Chaos God Slaanesh, the Maelstrom is, as far as Imperial scholars can ascertain, a naturally occurring phenomenon.Screaming Vortex - The Screaming Vortex is one of the so-called "Great Warp Storms" that separates the Calixis Sector of the Segmentum Obscurus from the Koronus Expanse region of the Halo Stars. It takes the form of a vast, seething cauldron of empyreal energies which, while not as large, are every bit as intense as those spewing forth from the Eye of Terror, the Maelstrom or any other such Warp/realspace overlap in the galaxy. The Screaming Vortex is a region of space beset by the unreal forces of the Empyrean, where the thin skein between reality and that impossible dimension has been torn viciously asunder. A volume of space far larger than the average Imperial sector is to all intents and purposes cut adrift from the physical universe, the laws of nature no longer applying within.Storm of the Emperor's Wrath - The Storm of the Emperor's Wrath is a notable and fiercely persistent Warp Storm which has raged since the Age of Apostasy in the 36th Millennium. It is believed by the Ecclesiarchy to have been created by the Emperor Himself to indicate His displeasure with the attempt of the renegade High Lord of Terra Goge Vandire to seize control of the Imperium during the Reign of Blood. It is currently consuming much of the Caradryad Sector.Van Grothe's Rapidity - The Warp phenomenon known as Van Grothe's Rapidity pulses on the Eastern Fringe of Imperial space. It is a purple-glowing whirlpool of destruction that extends across light years of territory and spells destruction for those desperate or careless enough to enter it without caution. However, the Rapidity is not without its uses, for though dangerous, it is also considered relatively stable by Adeptus Mechanicus Observators. It is of incalculable value to the Mechanicus Explorator fleets and Rogue Traders who regularly pass through this region. When traversed correctly, it can hurl a Warp-borne spacecraft through the eddies and tides of the Empyrean with such speed that an interstellar journey through Warpspace can be shortened by solar months, if not standard years. As a result of this effect, despite its hazardous nature, the Rapidity has earned itself the moniker of "Hell's Slingshot." The world of Medusa V was settled in the 37th Millennium by the Imperium to act as a way station for vessels seeking to make use of Hell's Slingshot, but was scoured clean of life in the 41st Millennium following the events known as the Fall of Medusa V by a Warp Storm spawned by the Rapidity itself.