Phyrexia
Phyrexia is an artificial plane of entirely mechanical "life" created by an ancient planeswalker. Little is known of this planewalker, aside from the fact that he enjoyed assuming the form of a dragon. This world was not so different from Mirrodin until Yawgmoth arrived. Yawgmoth, and the remnants and descendants of the phthisis-inflicted Thran whom he "saved", lived on this plane.
Structure of Phyrexia
The plane consisted of nine nested spheres, each with its own purpose and, often, mechanical ecosystem.
First Sphere
First Sphere of Phyrexia is a mechanical parody of life. It's covered by artificial jungle bedewed by oily rain. Streams of oil also run through the first sphere's landscape. It's home to a few forms of dragon engines and many others mechanical animals simulating true life. Rusting artifact debris lay around long plains filled with metallic dust and soot. Huge furnaces spew ash into the air. Newts are brought to this Sphere, likely to select those worthy for completion.
Second Sphere
Scraps and ruins from the first sphere are contained in the Second Sphere. Metal beams, pipes, and other structures make up the roof. Smokestacks from lower levels also appear in this level of Phyrexia. These are all that offer any source of light. Gargantuan ammunitions dumps as large as entire communities are located here.
Third Sphere
Third Sphere is filled with metal pipes creating space distortions that prevents planeswalking to lower spheres. Horrors of Phyrexia stalk this place.
Fourth Sphere
Fourth Sphere is where the primary Phyrexian population exists. Here are more smokestacks, as well as the vat facillities where newts are grown and compleated. Vat priests work here, monitoring the Phyrexian newborn and performing the operations of transforming them into Phyrexian machines and warriors.
Fifth Sphere
Fifth Sphere is the ocean of glistening oil used by Vat Priests of Fourth to breed newts, called the Boiling Sea. A massive steam creature also lives here.
Sixth Sphere
The Phyrexian Inner Circle is housed here. Essentially a realm for the Phyrexian governmental body, here are the most prestigious of Yawgmoth's servants, such as Phyrexian Demons, the Praetors, and other officials.
Seventh Sphere
The Seventh Sphere of Phyrexia is an eternal furnace of flames used to both power the plane and punish those who have failed Yawgmoth. Gix is the only Phyrexian known to survive the Seventh Sphere. It is a hellish place known as the 'Punishment Sphere'. Prisoners, artificers, and failures of any sort are brought here for torture. Phyrexian Gremlins live on this Sphere.
Eight Sphere
The Eighth Sphere is a place of pure energy.
Ninth Sphere
The Ninth Sphere is the control center for all of Phyrexia. Up until the Invasion, it was where Yawgmoth resided in plotting his eventual takeover of Dominaria. Yawgmoth also stayed here, dormant within his sanctum for some time, while his minions acted in his will and saw to it that his plans were executed.
Phyrexian People
Militarization
Invasion of Dominaria
Post-Invasion
Map of Phyrexia
Note
The forums in Phyrexia.com imitate the 9 spheres of Phyrexia.