The Maddening Roar
Mabar the Endless Night is a blackened realm where the faintest spark of light is quickly devoured by the unending darkness. It is a plane suffused with negative energy and the antithesis of Irian.
Mabar is a realm where no light shines. It is a world that is home to demons and the creatures that go bump in the night.
On Eberron, one can be brought back after death as either an undead or as a deathless. Those that are undead are said to have been infused with the essence of Mabar, while deathless have been infused with the powers of Irian.