Deathwatch: Scything Talons
The Tyranids are possibly the most dangerous alien race the Imperium has ever faced. In forces and fleets without number, they are sweeping across the galaxy like a Great Devourer, and their advance seems inexorable, unstoppable. Single-minded, and possessed with a cunning to match their savagery, the Tyranids have only one purpose: to feed. They are the hunters, the whole galaxy is their grounds, all living things their prey.
The Tyranids might be the most bio-diverse race in the galaxy. Multiple strains of Tyranid exist, each bred for a specific purpose, and many Magos Biologos believe that humanity has only ever observed only a small fraction of the currently existing Tyranid strains. The species evolves at a rapid rate, quickly assimilating traits it has consumed, or making new generations of Tyranid combat strains within days to combat specific threats in a combat theater. Each combat strain of Tyranid is armed with naturally deadly weapons, from sharp talons to plants that tangle men in dangerous plants; from symbiote creatures that disgorge flesh boring insects to excretory organs that ejaculate venomous fluid.
What drives Tyranid evolution, and directs combat strategy is the Hive Mind, a psychic consensus construct that is formed from the minds of all Tyranid. Linked together by psychically capable creatures in a phenomenon known as “synapse,” all Tyranid life contribute to thought, like a giant brain. The consensus of the one is the consensus of all, and vice-versa. This, among other things, is the source of the dreaded tenacity and ruthlessness of the Tyranid race.
The purpose of the Tyranid race seems simple: to feed. To evolve, they require more and more biomass. To obtain biomass, they must reap a bloody harvest from the living beings of the galaxy, killing all to serve as nothing more than gruel. They feed for the purpose of feeding, a species that thrives on annihilation. Even the very planets they terrorize are seen as nothing more than fodder, for they perform upon them an act which is the most terrifying of their deeds: they consume the planet, and all possible life within it. Every mineral, every microbe, every breath of air, until even the atmosphere is absorbed and what is left is a hulk so fragile and hallow that gravitic forces eventually break it down into small asteroids.
Tyranids might seem dumb at first, sending wave after wave of relatively fragile creatures in endless number to break upon the rock of any defense. But these are often only mere recon-by-fire, a probing strike that consists of the sacrifice of thousands of organisms (it matters not how many die, for in the end, all are re-harvested anyway). Later, the Tyranid enemy will often exercise a kind of animal cunning, using tactics to flank, evade, skulk, or stalk; actions that you would not expect from such reptilian-seeming creatures. Whatever the case, the Tyranids are often still much more prone to utilize head-on assaults with hundreds of creatures. The casualties Tyranid suffer are of no consequence. For they are truly without number, then the results are predictable: victory by attrition.