Commander Farsight - Mont'ka Denied: Over and over again, the Tyranid leader-beasts were hunted and destroyed by the pinpoint application of firepower, and over and over again, they were reinforced by fat-bodied Mycetic Spores that rained out of the skies. Thousands of citizens died every day as the insidious invaders probed at every defence and settlement, exploiting the least weakness to break through in a tide of chitinous bodies to slaughter those inside. Each time Farsight adapted his strategy, optimising military protocol to better slay the foe, the Tyranids would reinforce and adapt in turn. Though it burned him to admit it, O'Shovah's plan to cut off the head of his monstrous foe was not working.Calling an emergency council, Farsight convened with the greatest minds of the enclaves. His old friend, O'Vesa, was still clinging to life by virtue of a cocktail of age-regressive drugs of his own invention. He suggested that if the art of the killing blow was not working, then perhaps the patient hunter might be given a chance. Farsight's brow wrinkled, but he gave the idea full consideration nonetheless. Their world was ripe for the plucking, on the brink of being devoured by the Tyranid hive fleet above. As horrifying a notion as it may seem, perhaps they should not try to prevent the attack.Instead, they would allow it to happen, and then strike back.The very next night, Farsight and his seven most trusted commanders escorted O'Vesa to Vior'los' Earth caste research facility, Fio'ro'tl, deep in the Valley of Dust. Given enough time, the ancient scientist believed that he and his colleagues could develop a countermeasure that could destroy the Tyranids before their final triumph. O'Shovah knew that this was their last chance. With his planet all but overrun, he gave the order for the rest of the T'au upon Vior'los to evacuate.Before the week was out, there were only twelve T'au left on the entire planet -- Farsight and his seven Battlesuit Commanders, O'Vesa, and three of Lub'grahl's most capable Earth caste. Using samples of the xenos biomass gathered from the battlefield, the veteran scientists worked night and day to develop a biological countermeasure, their research facility guarded by six XV8 Crisis Battlesuits, an XV88 Broadside Battlesuit, and one of the few XV104 Riptide Battlesuits that had been "accidentally" diverted to the Farsight Enclaves from the ships en route to the Mu'galath Bay campaign. Though O'Shovah had deliberately kept the facility's defences as small as he dared in order to escape detection, on the eighth day, the swarms found them nonetheless. Thousands of scuttling weapon-beasts poured through the gullies and valleys from every direction, blade-limbed colossi stalking in their midst. Farsight relayed his greatest of respects to his honoured comrades and prepared to give his life to buy O'Vesa a few more precious seconds.The battle that unfolded between the Battlesuit Commanders and the Tyranid swarms was the stuff of legend. Ob'lotai 9-0, the XV88 Broadside Battlesuit operated by the AI engram of Farsight's old team leader, bullseyed dozens of Tyranid leader-beasts from his vantage point atop the research station. The seventh Commander Brightsword's Fusion Blades blazed bright as they cut through the giant battering-ram monsters that assailed the gates, alien ichor evaporating into choking clouds around him as he felled one, boosted away, then slashed through another. Wise Commander Arra'kon moulded complex firing solutions to defend every new ingress, coordinating the Flamer blasts from Commander Sha'vastos and Commander Torchstar to consume the greatest number of the lesser weapon-beasts wherever they scuttled through the rocks. When a towering monstrosity killed Shas'O Varg'ha with a blast of bio-electricity, burning him to death inside his Riptide, Commander Bravestorm, long interred within his life-supporting battlesuit, charged underneath the Tyranid Bio-Titan's midsection. Powering his ancient Onager Gauntlet to maximum, Bravestorm punched out its thorax in a gory salute to his fallen comrade. Meanwhile, Farsight duelled with the hissing leader-beast at the swarm's heart, matching the Dawn Blade against the hive creature's crystalline swords. Even O'Vesa was able to join the fight at the last, remotely accessing the interface of the fallen Riptide and bringing its weapon systems back online in order to deliver the deathblow to a squat-bodied broodbeast that was birthing lesser Tyranids straight into the facility's corridors.Suddenly, a great cloud of dust whirled up, obscuring the combatants as the Manta missile destroyer Or'es Por'kauyon hovered above them. O'Vesa signalled to Farsight that he had summoned the Air Caste's finest to extract them; the deed inside the facility was as good as done. One by one, the Battlesuits boosted up into the air and boarded the Manta. Below them, the research facility was buried under leaping Tyranid bodies as the T'au made their escape. Of the brave Earth Caste scientists, only O'Vesa survived.Over the course of the next few cycles, the world of Vior'los was stripped bare of every last shred of biomass. The ribbed mouthparts of the hive fleets had descended to feed, hungrily sucking up the rendered down gruel of their conquests from the many digestion pools below. Farsight and his commanders monitored the vile spectacle from high orbit. As the twin flames of grief and anger twisted in his gut, O'Shovah began to doubt the course they had chosen. When he cast a questioning glance across to O'Vesa, the wizened scientist just smiled and pointed back towards the bio-ships themselves. Farsight saw nothing at first, but soon, a black stain began to spread across the chitinous flanks of one of the Tyranid vessels. Within a matter of only a few moments, the affliction had spread to a second ship, followed swiftly by another and then another, until none were free of the malign tendrils. The bio-ships shuddered and writhed as the discolouration blossomed outwards to cover them entirely. One by one, the fleshy Tyranid vessels fell into themselves, rotting and falling away like a piece of fruit decomposing in a matter of seconds. Before the hour was out, the bio-ships had disintegrated entirely.The countermeasures the Earth Caste had made, explained O'Vesa, had been a suite of self-replicating poisons. The necrotising agents had been on time-delayed release in order to ensure they were fully taken inside the Hive Fleet before activating. The vector of transmission had been the bodies of the Earth Caste scientists themselves; they had imbibed the poisons as their last act upon Vior'los. Once their bodies were broken down in the digestion pools, the bacterial codes they had locked within themselves infected the air itself. As O'Vesa had hoped, the Tyranids had even stripped most of Vior'los' atmosphere away to fuel their further conquests. In doing so, they had doomed themselves to a swift and painful death.