The tyranids work as a swarm, with the sheer strength of the horde being enough to overwhelm most forces. The amount of close combat specialists in a Tyranid army can destroy most armies by themselves. However, if a target is too heavily armoured, the tyranids will adapt, using psychic artillery platforms known as zoanthropes. Tyranids first begin the invasion of a world by sending in infiltators known as genestealers and lictors. The latter is a camouflage specialist, equipped with scything talons and rending claws to assassinate high priority targets. Genestealers are pack animals that can implant eggs into unwilling targets that take over their bodies, thus creating hybrids. These hybrids then begin casting a psychic beacon to the rest of the hive fleet, all but dooming the planet to be eaten.
When the swarm arrives, they first send down horde upon horde of terma and hormagaunts, and the tervigons that spawn them. As support, they also send gargoyles, which are flying termaguants, and raveners. To command these numerous beasts, instead of a large synapse creature, they instead send Tyranid Warriors, medium sized beasts with a wide range of weaponry to choose from. To undermine the enemy's effort to repel them, the Tyranids will introduce toxic spores into the atmosphere which invade all non-Tyranid organisms and begin to digest them from within.
As the hordes of gaunts do their work, they will inevitably reach locations where resistance is simply too much even for their near-unlimited numbers. Thus the hive fleet begins using beasts known as carnifexes, zoanthropes, biovores and the dreaded bio-titans, the Tyranid Tervigon. Carnifexes are the Tyranid's tank analogue, large, lumbering, well armoured beasts that can take a beating and dish one out. They have the largest range of weaponry and bio-enhancements recorded, ranging from crushing claws to scything talons, to barbed stranglers to spore mine launchers. Zoanthropes are purely psychic creatures, lacking limbs to move around they levitate using their psychic powers. They are normally pressed into an anti-armour role, their massive psychic power turned on the mere steel of the Imperium's tanks. Biovores are Tyranid artillery, shelling emplacements with spore mines, which explode and begin digesting all those in contact with them. Tervigons are giant raveners, large enough to swallow Chimera APCs whole. Tervigons are only seen where the fighting is harshest and normally spell the end for whatever resistance is on the planet.
In the last stages of a planet's demise, the Tyranid forces will begin to gorge themselves on the fallen, eating anything living. They then move to large digesting pools, into which they throw themselves, commanded by the Hive Mind. Here they are broken down into their base components, and are later taken up by mycetic spires, to be returned to the fleet's hive ships. Here, the DNA of the resistance is analysed for stronger adaptions, which are then added to the fleet.