The swamplands of Mephidross are a large expanse of foul water covered over by a scum of black ichor. It is a toxic wasteland of ooze, filth, and corrosion.
From a distance, the sky above the Dross looks like ink swirling in water. As you approach it, the ground begins to soften, leaving spongy footprints in the land. But the most striking feature of the Dross is the sound it makes. The whole swamp hums with a low, dissonant chord. In some places, it sounds like a distant generator. In others, it's deafening. Some report hearing whispers beneath the constant thrum. The sound comes from the chimneys of the Dross, ominous structures that "grow" seemingly at random throughout Mephidross. These "smokestacks" range from ten to three hundred feet high. All emit the sickly green corrosive gas called necrogen that slowly saps the life from creatures, turning them into nim.
In the center of the swamps is Ish Sah, the Vault of Whispers, a large fortress that was used to control the activities of the swamp. Here Geth, the ruler of the Moriok, dwelt. The Black Lacuna was also located in the Mephidross.
During the Leveler War against Memnarch's machines and the Nim, the Mephidross advanced exponentially into the other territories until the mad guardian was put down. During the advance of Phyrexia, the Dross expanded also, swallowing large parts of the Tangle and the Razorgrass Fields. The Seven Steel Thanes now rule fiefdoms within the area, jockying for control over the swamplands.
The Moriok, the human occupants of the Dross, lived in scattered communities throughout the swamp. The evil magic of the Necrogen Mists affected the Moriok's brains, exacerbating their natural human tendencies toward hate, aggression, and greed.
Nim, the zombies created by the Necrogen, vent the gas themselves, as well. They were very numerous and, along with the already horrible conditions of the environment, made this region inhospitable to most life. The leonin and the people of the Razor Fields were the bitter enemies of the nim.
Vampires lived deep within the Mephidross, in areas inhospitable even to the Moriok. The warlord Geth once claimed one of these creatures as his champion, proclaiming it the sole member of its species.
- Doug Beyer (December 08, 2010). "The Nonhuman Cultures of Mirrodin". magicthegathering.com. Wizards of the Coast.
- Jeremy Cranford (February 03, 2004). "Creating Mirrodin: Swamps and Zombies". magicthegathering.com. Wizards of the Coast.
- Magic Arcana (May 19, 2004). "Sketches: Nim Grotesque". magicthegathering.com. Wizards of the Coast.
- Rei Nakazawa (September 09, 2003). "Mirrodin Image". magicthegathering.com. Wizards of the Coast.
- Monty Ashley (October 28, 2010). "Sketches: Corrupted Harvester". magicthegathering.com. Wizards of the Coast.
- Doug Beyer (November 17, 2010). "The Human Cultures of Mirrodin". magicthegathering.com. Wizards of the Coast.