Mechanicum

Glowing lava poured in mighty waterfalls from shattered aqueducts, and rivers of blazing rock oozed through the streets, consuming all in their path. Altered skitarii and warp-enhanced Protectors perished as they were swept away by the searing tides of molten lava.

Soon the city was ablaze from end to end, the magma incinerating anything flammable and melting anything that wasn't. In moments, thousands were dead, attackers and inhabitants both, though such a death was a mercy for the denizens of the Magma City.

The Typhon Causeway cracked at its midpoint, a kilometre-long slab of rock shearing away from the city and tipping more than ten thousand men and war machines into the lava. Wrenched and torn by quakes wracking the city, the Vulkan Gate, which had guarded the entrance to the city for a millennium, fell and broke into a thousand pieces.

In the age to come, these would prove to be the only things to survive the cataclysm.

Thousands streamed from the city through the wreckage of the landing fields where Tempestus had made its last stand, but such was the overflow from the shattered aqueducts that no escape was possible. An ocean's worth of magma spilled outward, and the heat and fumes soon overtook those few who could outrun the lava.

Only Aquila Ignis escaped total destruction, Princeps Camulos turning and marching at flank speed to avoid the tide of molten rock. Even he was not quick enough, the lava flowing around the Imperator's mighty legs and steadily burning through its shielded plates. Aquila Ignis waded through the lava for five steps until at last its armour failed and its ankles gave way.

At last the towering engine was brought down by the fury of the planet, its immense bulk crashing to the ground, smashed to destruction on the hard rock of Mars. Its bastions crushed themselves, its cockpit decks were flattened by its unimaginable weight and only its Hellstorm cannon survived the Titan's fall.

In time, this would be salvaged and taken to another world, but for now it had no more death to deal.

The destruction continued within the city as the lava eagerly rose up through the streets to claim what had been denied it for so long by the technological wiles of the Mechanicum. Within an hour, nothing remained alive within the Magma City, every living soul burned to ash and every structure brought low.

Three hours after Adept Koriel Zeth unleashed doom upon her forge, the Magma City finally sank beneath the great inland lake of lava. The last of its towers were cast down, Zeth's inner forge filled with lava, and all her great works were destroyed as thoroughly as though they had never existed.

And with their destruction, all hope of lifting the Imperium into a golden age of scientific progress, not seen since humanity set forth from its birthrock, was lost forever.

Addenda

+ Far below the Martian plain, the last two Knights of Taranis made a cautious descent into the rocky depths of the Medusa Fossae, a trench system that straddled the border between the highlands and lowlands of Tharsis and Elysium. Both machines clambered down into the darkness while Mars above burned with war. They were each scarred with battle, yet both moved with smooth natural grace, as though fresh from a maintenance refit. Equitos Bellum led the way, with Pax Mortis guarding their rear as they sought an automated research facility of Koriel Zeth that Rho-mu 31 had assured them they would find hidden in this deep canyon. Here, the Knights and their two passengers would follow the instructions of the girl with the golden light, and await the end of hostilities to see what was left of their beloved world. +

+ Deep in the Noctis Labyrinthus, Dalia Cythera and Rho-mu 31 took up their stewardship of the Dragon. A measure of the golden light that shone within Dalia had now passed to her Protector, and they were content in the knowledge that their friends were as far from the fighting as it was possible to be. Only much later, when Dalia dared return to the silver cavern, did she see that the book containing the grand lie of Mars had been taken. +

+ Ten thousand years would pass before the next Guardian was drawn to the Noctis Labyrinthus, but by then the damage had been done. +