The rock above and below began to shake as the distant roar of the screaming Green Tide closed in on the single structure within the vast underground cavern. Pushing and shoving to be the first through the narrow tunnels that fed into this large cavern, the Tide was chaotic, and without a leader, this was no organized war band but a loose party of savage Orcs. Not to be underestimated, the muscular brutes grew under a gravity five times that of a standard Terrain gravity, making their bone structure and strength leagues above that of a normal Orc.

Their hearing however was just as mundane as every other Orc and perfectly attuned to the wavelength that now resonated with a high-pitched klaxon which bounced off the tunnel to reach far into the depths of this dark cave system.  Wielding pieces of jagged metal as clubs and armored in whatever scraps they could fashion together they climbed up the brittle rock embankment that surrounded the isolated structure that was little more than a round metal hut. It took several tries before the Orcs could find purchase in the loose rock that broke apart under their strong grasp. Like a flood, the Green Tide found a suitable path and they all followed suit in a sprint once on the same outcropping of rock as the metal hut. 

"Execute." 

CLICK

A mechanical whirring drowned out the screaming Orcs mere milliseconds before a heavy thud sounded from the metal hut. The sides split apart and orange Promethium spilled out from the round warhead centered in the middle of the cave. The Orcs were too enraged to even notice as they continued to charge directly into the flames, as if perfectly content to swing and bash at the fire itself even as it consumed them.  

As the fire consumed the bulk of the Green Tide, armored warriors dropped from concealed positions to block the tunnel exits the Orcs had just taken to enter the cavern that was quickly becoming their tomb. The armored warriors acted with precision as they connected heavy ceramite shields into an interlocking mesh completely blocking the egress routes of the now panicking Orcs. 

"Team one to Station, in position." 

"Team two to Station, in position." 

"Team three to Station, in position." 

"Team four to Station, in position." 

"Team five to Station, in position." 

"Station to all Teams, brace for Gravitron Blasts" 

Each of the teams blocking the exit locked their armor to counterbalance the residual effects of the super-increased gravity that was about to decimate the remnants of the Orc throng. Even several hundred yards away from the orcs the cannon fire from the Brokhyr Thunderkin would have residual effects on the Hearthkyn Warrior Oathbands.

Deep thunderous roaring bellowed out from the intricate cannons hefted into position by the Thunderkyn Exo-Suits that recoiled back with each shot. The positioning of the Thunderkyn had to be precise as the loose rock would potentially collapse if a poor landscape was selected for the firing line of the Oathband Combat Engineers. 

A Thunderkyn standing aside the firing line with far more scars gouged into his Exo-suit chewed a piece of Yu'Lok root as he tried not to lose interest in the skirmish. More Orcs, more mindless slaughter, hardly a test of their mettle but a job that needed to be done nonetheless. Despite staring directly into the Orc throng he timed the firing line procedures more on experience than observation as the carnage on the other side of the cavern was hardly anything worth noting. 

"Hold fire, Thunder Ridge to Station, primary Orc element is neutralized." Opening his helmet's visor he spit the Yu'Lok root out. The damnable stuff was only good for keeping the vibrations of the Grav Cannons from giving him a toothache, his Cloneskein was unfortunately not the best suited to continual work around the specific hum of vibrations immitted by Grav weaponry, not that it was a huge concern but worth pocketing some of the root from the Mead Hall that morning.

"Received, Station to all teams you are clear to engage at will, watch your crossfire." 

The Hearthkyn acted as one despite each team being separated by several hundred yards, silent communication consisting of symbols and markers on each other's HUD alerted them to changes and movements in the greater force. 

"STEP!" yelled a Theyn to his shield bearers. "STEP!" Each cadence marked a slow but gradual movement in the teams. The orcs were still far enough out that the cadence wasn't entirely needed but all Kinhost understood the value of routine maintenance of a skillset. 

"BRACE!" A Theyn yelled as a few dozen Orcs slammed into his shield bearers. They could have gunned them down with the HYLas Auto Rifles or Autoch Pattern Bolters that each Hearthkyn wielded but this lot wasn't worth the ammunition. Ranged weaponry clicked into storage position against backs as plasma blades and various concussive melee weaponry were chosen instead. Yet further carnage unfolded on the other side of the shield wall with only the guttural death roars of the Orcs indicating what was happening behind the rolling metal tide.

"If there was ever a Kin that wore a grimace on his helmet, it be you Khesdrem." The Ironmaster that had spit the Yu'Lok root out earlier said as he walked up to stand beside the Boneweaver. 

"Hm, it is a strange thing to wish for practice in one's trade, when one's trade requires a Kin to be slow to deflect a blow." Khes replied to his old friend, Havtum Warmane, the Ironmaster. 

"You'll not feed the void with your rust, Weaver, you know this to be true. Plenty of injuries in the foundries to keep you busy when you finally decide to retire from watching the youngsters toy with the enemy." Havtum placed a heavy gauntlet on the more nimble framed armor of the Boneweaver. The Ironmasters Exo-suit dwarfed even the sizable bulk of the Void Armor worn by Khes, a requirement of any heavy weapons role such as the Thunderkyn.  

"Mayhaps I should accept that my time in the void is coming to an end and my skills will be better suited to the Hold... but not this day old friend." He added the last bit as he noticed a Hearthkyn vital signature stagger, indicating an injury. The armor he wore was more flexible than most Kin Warriors, allowing him to quickly reach injured and be where he was needed most at the right time. In this case, Khem needed to cross a thirty to forty-foot chasm to reach the injured Hearthkyn, most Kin would be too slow and heavily armored but Khem's lighter Void armor allowed him to use one of the few propulsion packs available to his kind. Mid stride he activated the pack and flew over the chasm with little effort, he could already see the injured party that had moved behind the shield wall that was still advancing. It was standard procedure for injured parties to move out of the way and the rest of the host to move onwards as tending to wounded mid-fight was a recipe for disaster. Not to mention the armor worn by Hearthkyn was self-stabilizing to most inures and any advanced medical treatment would be beyond the skill of the average warrior Kin.

Lying prompt up against a brittle rock that he had partially collapsed into, the warrior's leg had an obvious suit breach where a jagged piece of metal protruded. White foam was hardening around the foreign object as the armor attempted to stabilize any bleeding and reduce atmospheric venting if the environment was de-pressurized. 

"Seems I have a grudge to settle now." The Hearthkyn grunted through gritted teeth as Khem dropped to a knee and activated his Omni-scanner to see through the armor and triage the injury. 

"Easy there tanker, this fight isn't worth a grudge." Khem used a term of endearment for younger Kin fresh out of The Crucible. Given Khem's age, he felt it appropriate to call most of the Hearthkyn tankers as a few years under their belt would see most advancing past the basic infantry units.

As he spoke the Bone Cog attached to his belt unfolded into several spindly arms with a central body no larger than a belt buckle it served as an extra set of hands whenever treating injuries, the little robot lacked an advanced Cerebral Unit so applying pressure or cutting through surfaces was about all it was good for, which did allow Khem to use his hands for other duties, such as firing his HYLas Auto Rifle. Content to let the Boneweaver work the Hearthkyn accepted his fate as a "casualty" and the embarrassment that would bring with it, despite it being nothing but a lucky blow that the Orc managed to strike on his leg.