Tyranid Warrior
A Tyranid Warrior is a type of Tyranid that fills a leadership and heavy-assault role. Warriors are usually deployed at the earlier stages of planetary consumption. As they are synapse creatures,they spread out the synaptic web and guide the lower forms of gaunts in battle. They are also potent foes on the battlefield as they can carry many different biomorphs and weapon-symbiotes and their genus is used as a template to create various elite creatures of the Tyrannic host.
Even the smallest gathering, patrol or raiding party of the Tyranids will most likely be led by a Warrior in order to guide the lesser beasts and keep them connected to the Hive Mind. Think of them as a combination of an elite sergeant and living walkie-takie.
On the Tabletop
It is not an easy life for a Warrior as everyone, their grandma, and their grandma's cat all know the most important rule when fighting Tyranids; take out the synapse creatures. And being the most common synapse creatures and relied on to spread the web they will be targeted first and foremost (unless a rampaging Hive Tyrant or Carnifex is bearing down on them first). Because of this most games will see Warriors bear a great deal of heavy weapons fire and be turned into creamed goo before too long.
In early editions, these things were fucking boss. They could easily match Terminator durability since there was more wargear they could get, and they had much greater flexibility, too, due to how the rules were. You could very easily make a Warrior that was a close-combat death machine, ranged killer, or even a mid-level psychic powerhouse. Or all three in the same unit. In early editions, they could pack on extended carapace or even Warp Field for a good armor save; you could make them winged or leaping; and with the huge number of attacks they had, great stat-line, and tons of upgrades, they were a literal swiss-army commander, one that was extremely popular for newcomers. One might even say they approached pornographic levels of awesome. Sadly the recent edition changes, from about 5th onwards, just turned this mainstay unit into swiss cheese.
Now Warriors are one of the best units in the Tyranid army, with that HUGE price reduction (24 point with basic equipment, and 20 if you just go with 2 scytals) and the removal of instant death mean it's almost impossible to shoot them down in one hit except with heavy weapons, usually better used on the plethora of 8+ wound monsters tyranids can also field. While the new equipment table is reduced from past editions, they still have everything they need to fulfill pretty much every role on the battlefield: shock trooper, heavy support (now a brood of 9 can have 3 heavy weapons) or simply utility synapse. With a Prime around (also priced down) they even get +1 to hit both in close combat and in ranged. This is a huge bonus, considering the already good WS/decent BS stats of the Warriors. 3+ to hit and 3 attacks mean pain in close combat, and even with average 4+ BS the fact that all weapons they can have have 3 shots per gun makes sure a rain of death comes to the enemy. Their ideal loadout is double boneswords and a deathspitter as this gives them 4 attacks at strength 4 AP-2 in CC and 3 strength 5 AP-1 shots at range, making an excellent unit that can cause hurt to the enemies of the Hive Mind wherever the warriors happen to be standing. Long story short, 8th edition Warriors are veritable beasts that represent the fluff as well as possible. Overall powerful and resilient heavy units that will make the enemy shiver in fear.
Shrikes
Shrikes are a winged adaptation of the Warrior bioform. Just when you thought regular Warriors were bad enough, well they can fly now.
Fulfilling similar battlefield roles and allowing Synaptic coverage to extend to the fast-moving elements of the swarm, such as Gargoyles and Harpies which might otherwise outrun those Synapse Creatures incapable of flight and be separated from the Hive Mind.
While sacrificing some of the protection of their chitin carapace for the ability of flight, few enemies expect an assault of creatures as large as Tyranid Warriors from the skies which begs the question on what counts as "too large"? Anyways, this allows Shrikes to perform surprise attacks with great speed and efficiency, the element of surprise making up for their relative lack of protection.
Their speed and mobility as well as their large selection of biomorphs make them exceptionally flexible, allowing them to fulfill many battlefield roles from surprise assaults directed at the weakest elements of the enemy force, to filling gaps in the synaptic web at a moment's notice.
These flappy meat grinders have the same statline (right down to their 4+ save, something they missed out on in previous editions) and options of their terrestrial cousins, but with more mobility and the keyword FLY that allows them to fall back and still shoot, giving them more mileage out of their guns and solid mobility. They still have no official GW conversion kit so you’d best get to chopping those Gargoyle’s wings off...
Warrior Prime
Warrior Primes are an upgrade to the regular Tyranid Warrior. Due to a horrible case of Pretend (And looking almost exactly like a normal Warrior), there have been numerous misreports and misidentification within the Guard. This means that they usually prioritize the big, scary bugs over the smaller and much more intelligent Warrior Primes, you know, the creatures that is actually more dangerous than the Carnifex around the corner. Whether it is Just As Planned in accordance to the Hive Mind or the Imperial Guard is that incompetent in information gathering is unknown. But what is known is that it has cost more than one Imperial officer his rank and countless men their lives. To be fair to the Guard, the Warrior Prime has only been categorized in recent times as a different and dangerous threat. The Warrior Primes have been identified and reported to exist amongst the ranks of the various Hive Fleets, though many Imperial savants and Adeptus Mechanicus Magos Biologis are quick to point out that this is less likely to be because they are a recent evolution and more likely because they simply blend in with the other standard Tyranid Warriors.
Primes are also being encountered in greater and greater numbers within Hive Fleet Dagon, perhaps as a direct response to the constantly evolving tactics of Imperial forces and the Hive Fleet’s need to deal with the elevated Deathwatch presence in the Orpheus Salient after several costly encounters.
In military function, Tyranid Warrior Primes take on the role of junior officers within a Tyranid swarm. Much in the same way as a Hive Tyrant might lead a full host of Tyranids, a Warrior Prime will oversee a smaller section of the battlefield or direct a smaller strike force of warriors. When close to a more powerful synapse creature they will defer their control, acting instead like non-commissioned officers, often personally leading broods. However, should they find themselves alone, they can easily bind together those Tyranid creatures nearby into an effective fighting force and carry on with little trouble. In this way, a Tyranid Warrior Prime is just as capable of directing a swarm as a Hive Tyrant and many an Imperial officer has suffered as a result of underestimating their ability to project the Hive Mind and lead lesser Tyranid creatures.
On the Tabletop
Primes clock in at 100 points bare, which is five times the cost of a normal Warrior. In return you get a significantly beefier profile: it has a 3+ save, its WS, BS, S, T, A and LD are all improved by one and it has double the wounds. It also grants the Alpha Warrior ability, giving rerolls of 1 on all To Hit rolls to all Warriors and Shrikes within 6". Shrikes likely won't benefit much, but Warriors do. WS3+/BS4+ are not bad, but the rerolls will really help to make them even deadlier. Pack your Prime in with some normal Warriors (because it has 6 wounds it can't be targeted unless it's the closest model) and go to town. A problem that the Prime has however is that it's slow, limited to only 6" movement. You could pack it into a Tyrannocyte or a Trygon tunnel... except RAW you can only fit one unit in here, so you'll have to pick either your Warriors or your Prime. The best way you could make this work is to deploy your Prime this way, charge in a unit of Shrikes and have the Prime join the fray. But to pull something like that off requires you to be some sort of tactical genius...