Orks - Gathering the WAAAGH!: First and foremost amongst all of the Orkoid instincts is the literal need for an Ork to wage war. Orks need war just as a Human or Aeldari needs food and water and over the long millennia of their existence the Greenskins have become very, very good at it.Due to their inherently aggressive nature, Orks constantly fight amongst themselves to prove who is the strongest, sharpening their in-born warrior skills and weeding out the weak, though this process usually poses little threat to the larger galaxy.However, Ork populations can reach a form of critical mass that can unleash a full-scale interstellar migration of Greenskins.This violent migration and the planetary assaults that result from it is what Imperial savants refer to as a WAAAGH!, a crusade of pure aggression that crashes through multiple star systems in an absolute orgy of fury and violence.A WAAAGH! usually starts small, perhaps even as small as a single Ork, who is visited by the Orkoid deities Gork and Mork with dreams of great carnage. He will impart this vision to others of his kind through repeated blows to the head, or, if he is of a more intellectual bent, he will build a great Ork war machine like a Gargant that is the very image of his savage Gods.Rumours of the coming WAAAGH! will spread through the local Orkoid society and the Orks begin to unite. New warbands join the growing throng with every passing day. An Ork warboss will fight his way to the top of the hierarchy of this growing Greenskin horde and earn the status of a warlord, adding the armies of those tribes he conquers to his own horde.As news of his new position spreads, the trickle of Ork reinforcements will grow into a green flood. Ork Meks will begin to collaborate on more and more outlandish projects, building ever larger war machines and weapons for the WAAAGH!Smoke-belching mobile fortresses and titanic war engines are cobbled together out of nothing more than heaps of scrap metal and the always heavy-handed enthusiasm of the Greenskins, another side-effect of the growing gestalt psychic energy of a WAAAGH!With each victory, the new warboss' legend grows, and more followers flock to his blood-soaked banner. As he fights to retain command of his ever-growing horde against a constant stream of challengers, he will subsume the armies of those he conquers into his own tribe, and as news of his prowess spreads ever further, the trickle of reinforcements becomes a green flood.Drawn in by the warboss' reputation, Ork Meks will start to collaborate on more and more outlandish projects as the WAAAGH! grows, building even larger war machines and gunz. Smoke-belching mobile fortresses and titanic engines of battle are cobbled together out of nothing more than scrap metal and heavy-handed enthusiasm.Gorkanauts and Morkanauts appear in growing numbers, their pilots seeking out the WAAAGH! with a feverish intensity. Whole mobs of Mekboyz raise towering scaffolds within which Stompas and even Gargants start to take shape, these mighty effigies igniting some primitive drive within the minds of the Orks who see them, causing the flow of WAAAGH! energy they subconciously generate to reach fever pitch.At this stage there is still much rivalry between the various klanz and tribes, and each will strive to outdo all the others in terms of the sheer destruction that can be wrought by its war machines. Those Meks without the resources to construct Stompas and Gargants will instead create mobs of clanking Killa Kans and Deff Dreads, or Battlewagons from which the warbosses can lead their armies to war.Soon the emergent WAAAGH! begins to span worlds instead of just continents. Entire native populations are forced into slavery merely to manufacture ammunition for the horde's guns. Crude factory-ships and war hulks are bashed into shape, the better to transport the Ork armies into battle.When the lure of imminent bloodshed can be resisted no more, the deadly fervour washing through the horde overflows. Teeming Ork armies mass and swell with a roar like savage oceans, and the skies fill with crude and bulky Ork space-faring vessels.Whilst these masterworks of destruction take form, even more Greenskins are drawn towards the horde by the impending promise of these massive war engines' use and the exciting carnage they will reap. Most of the Ork Boyz of the horde simply relish the chance to get into a really good fight. But those amongst their number who dream of becoming part of a truly awesome vista of destruction often choose the roles of crewmen and gunners on mobile Battle Fortresses and Stompas.There is always a great deal of continued rivalry between the klanz and tribes of a WAAAGH! and each strives to outdo all the others in the sheer "killyness" of their war machines. Those Meks without the resources to construct towering Stompas or Gargants, the Ork equivalents of Imperial Titans, instead create mobs of Killa Kans and Ork Dreadnoughts, banding their creations together to form armies of mechanical savages that dwarf the mobs they march beside in size and power.Others build the fleets of Fightas, Fighta-Bommerz and Bommerz that are laden with gunz and bombs that will assault their foes from the air once the battle begins.The grand musters that precede a full-scale Ork invasion are an awe-inspiring sight. As the Orks gather for battle, smoke from thousands of oily engines fills the sky.The ground trembles beneath great wheels, tracks and the thunderous strides of towering Gargants. Armies of Greenskins stretch across the horizon, raising their banners high to proclaim their reputations and allegiances, their warcries audible for miles around. Looming Gorkanauts and Morkanauts, bizarre artillery pieces and force field generators chug, clank and buzz amidst the green throng.Armadas of rusty vehicles raise roiling thunderheads of dust into the atmosphere, whilst Dakkajets roar overhead leaving contrails of filthy smoke. Speed Freeks rev their engines, and the Boyz fire their guns into the air as a carpet of Gretchin spreads out in front of the army.Eventually, the battlefield is barely visible beneath the endless sea of green, each Ork warrior certain that the ground will soon be stained red. Here the power of the WAAAGH! is palpable as a wave of raw aggression, and the Orks believe Gork and Mork are gazing eagerly down from the Warp to see how their warriors will fare. Then as one, with an almighty bellow, the Orks surge forwards, and another world is plunged into unending war.Those Greenskins that do not aid in the construction of the WAAAGH!'s war machines seek out like-minded fellow Orks who fight in the manner that most appeals to them. The Orks call these groups kults, of which the vehicle-obsessed Kult of Speed is the most widespread and well-recognized in the Imperium, though by no means the only kult that exists in Ork society.The Stormboyz and Flash Gitz also represent kults, while those Orks who are unusually sensitive to the growing pool of gestalt psychic energy surrounding a gathering WAAAGH! may become Madboyz.Hundreds of other Ork warbosses will add their own armies to the cause of a new WAAAGH! as the Greenskin assault begins to spread across whole star systems rather than just a single world. Entire native planetary populations are forced into slavery to their new Greenskin masters to manufacture ammunition for the horde's guns and other materiel that the WAAAGH! requires.Crude factory-ships and war hulks are bashed together to produce further transports for the horde, while a truly large WAAAGH! may ultimately infest a space hulk to move from world to world or even hollow out asteroids and create the massive spaceborne Ork fortresses known as Roks.When the lure of battle can no longer be resisted, the WAAAGH!'s savagery reaches a fever pitch that can no longer be contained save by the spilling of blood in vast quantities.The Orks who launch a WAAAGH! generally have little in the way of a coherent combat doctrine like the other major intelligent species of the galaxy. Their only goal is destruction and mayhem in as large a quantity as they can muster.The Orks are a plague upon the other civilisations of the universe, a race of genetically-engineered bioweapons whose true purpose was lost eons ago but who still carry on the fight -- against anyone, at anytime -- for no reason other than their own joy in destruction and slaughter.Once an Ork WAAAGH! has gathered, with one almighty bellow to the heavens from millions of Ork throats, another world will be plunged into unending war beneath a surging green-skinned tide.