A Legions Imperialis diorama from Warhammer World.
Magma City was one of the last Loyalist strongholds on Mars, a bastion of high technology defended by the survivors of the Death of Innocence. High-Adept Koriel Zeth, sovereign of Magma City, fought a desperate defence against overwhelming odds, battling Traitor titans and the warped creations of the Dark Mechanicum. Rather than surrender, Zeth chose to trigger a cataclysm which flooded the city in lava, destroying Loyalist and Traitor alike.