So I've been thinking of a few chapters to make up on my own. I really like the Salamanders, but I didn't particularly like their fluff, so I made a new chapter that sounded just cooler in general (to me at least )

I call them the Scorched Hellions. A spin-off from the Salamanders, they were deemed unruly, even for Space Marines. Thus, they were given a task deemed unfit even for servitors: protecting the mineral refineries and mines of the molten planet Vesuivius - a world rich in the items neccessary to produce ceramite and other alloys of need in the Imperium. Akin to a desk job at a law enforcement agency, the Space Marines succumbed to boredom, except for those lone few who were sent to reinforce war-ridden subsectors.

In their spare time (of which there was much near the beginning) they studied the molten planet and the other planets within the subsector (aptly named The Ring of Fire, due to the many molten and volcanic worlds of the sector). They began to study new ways of creating environmental armor to protect the wearer against even the hottest plasma. Thus came to fruition their specialty: they were sent to planets with the most inhospitable climates or extreme circumstances to purge them of xenos or Chaos. They trained relentlessly for the next few centuries, perfecting their special breed of warfare.

In M40, they were called upon by the local planet of Herculaneum, an Imperial Guard outpost and refinery-world. There was no indication of what enemy was assaulting the planet. Making all due haste in their battle barges Pompeii and Krakatoa, a force nearly 500 strong arrived in orbit around Herculaneum expecting en masse ordnance from the planet from any possible attackers. Scans revealed no life signs on the surface, and the volcanic world's only habitable zone near the south pole was obliterated by massive artillery. This was puzzling indeed to the captains and marines aboard. They commenced drop pod and Thunderhawk gunship missions to the surface as recon. Scouts noticed nothing unusual (besides the obvious). The Hellion chapter master, Ignacio Infernatus, called back his men from the surface. There was fighting to be had elsewhere.

Suddenly ruptures and earthquakes from the core of the planet rushed through the crust and mantle of the planet. Deep down there was a massive anomaly forming of unknown origin. Scout squads on the surface then reported hidden shafts leading many thousands of feet down into the crust of the planet. Whatever enemy was down there, it couldn't be a worse situation.

Techmarines created an elaborate jury-rigged system of elevators to take men down to the end of the shaft, some 2 miles below the surface where the heat and pressures would kill a normal man. Assault squads removed jump packs, scouts grabbed shotguns, tactical squads grabbed flamers, and terminators attached storm bolters and heavy flamers for the close quarters they would soon fight in.

The first squads to be sent down were obliterated. Just before comms went down, the last man alive shouted one word: Heretics. There were Chaos forces below the planet.

Ignacio ruled out sending more men down the shafts, but he soon came up with an alternative, but risky, plan of action. Techmarines, ever so capable, managed to attach high-powered drills (jury-rigged of course) to drop pods to drill down through the crust and do a tactical insertion right above the heads of the Chaos forces in a molten island surrounded by lava. The first wave, nearly 150 strong, led the first assault on the underground forces. The heretics were caught off guard and were soon torn asunder by flamer and bolter fire from behind them. The first wave was a success. However, a new anomaly formed again. Cave-ins caused rockslides and molten lava to jump and spew everywhere. Within the fortress, a dark ritual was being performed to summon a Daemon Prince. The price of its' arrival: The Space Marines and the planet. Ignacio's forces reached the inner bastion of the fortress but the Chaos Marines they fought were unwilling to give up so readily. Molten lava seemed the only way through the massive gate leading within, and so the Space Marines, using their special skils, managed to carve a hole through the wall by dipping their power swords into the molten liquids. The marines within soon died quickly, and at the ritual, Ignacio himself slew the fledgeling Daemon Prince.

After the Battle of Herculaneum, their talents were needed across the whole Imperium for those excessively extreme missions that others wouldn't take on. Such was the fate of the Scorched Hellions - getting the tough assignments.