This was posted initially on BOLS as a reaction and response to that terrible post 'looking' at Tyranids in 6th edition. Since we're doing such posts on 3++ (having done so for Daemons and Blood Angels so far), I moved this over here as well. I believe Puppy has another Tyranid post coming as well to see his initial thoughts on how they are adapting to 6th and fit into the fold.
Below are some initial thoughts in relation to how the rules impact Tyranids as a whole.
Relationship with vehicles - far, far, far more of an equilibrium. Consider this, every vehicle is now a toughness based model with no save where AV = Toughness and Wounds = Hull Points. For example, a Land Speeder (AV10, 2HP) would be a T6/W2/Sv- Monstrous Creature. A Rhino (AV11, 3HP) would be a T7/W3/Sv- MC. A Land Raider T10/W4/Sv- MC. Much easier to handle, particularly when they are WS1 at BEST in combat. Land Raiders may get to you but they won't last. Hive Guard shred everything short of AV13/14 and even then, two volleys can deal with AV13. They can still get cover saves, generally a 5+, but cover saves don't work often against Hive Guard or in combat. Sounds pretty damn good to an army which used to struggle in taking down vehicles.
Want to know what's better? Each time you take a 'wound' off a vehicle, it has a chance to die (much like Fateweaver). It's a 2++ to be sure since Tyranids lack AP2 (3++) or AP1 (4++) weapons in numbers but they are much more capable of simply removing vehicles from the board than before. They leave Wrecks behind which means your little guys are less likely to die but you offer your opponent better places to hide.
That being said, Flyers are still an issue. Dakkafexes/Tyrants are probably the best bet with a lot of medium strength, twin-linked shots (and no AP- negative modifier) but they are short-ranged and limited in durability compared to the other MCs. Flying MCs are probably the best answer here as well as certain psychic powers but without allies or any FAQ'd skyfire units for Tyranids, flyers could pose a problem.
Relationship with assaults - Fearless has no downside? Oh, no go to ground against shooting, that sort of sucks. But seriously? No downside in combat? *runs into combat* Lack of No Retreat wounds is huge. Massive. Ground-shaking. And it's not just the maligned Tyranids benefiting here (hello Daemons and Orks!) but it really improves their ability to tarpit and actually combat the enemy. Before, sending in Termagants all alone was a sure way to get them killed in one round, especially without Catalyst. Now, they can survive that 1st round and tie units up whilst the other guys come running in. With the ability to spawn Termagants from Tervigons and throw them into combat up to 24.999" away (19.999" average), that is some impressive mobility and ability to pin an enemy in place. This wouldn't be possible without changes to Fearless and charge ranges. This also means you can put MCs or other bugs into combat with the little guys and not take excess saves you shouldn't be.
However, not all is swell here. Terrain is still Tyranid's number one fear (amusing since they eat it and everything else at some point) as assaulting through it combined with Overwatch can leave you half the models you started with before you actually get to attack. Still waiting on those abilities which we can apply to a few squads (*cough Genestealers cough*) to circumvent this. Random charge length can also really hurt - Fleet helps make this more reliable but in many of my games there have been instances where a unit which should be in combat range (i.e. less than 7" which is the most likely combination on 2D6) falls short and gets blasted to little bits. One major issue here is when we encounter terrain - now random charge length is not only random, but likely to be shorter than not random. For an army which is more about combat than shooting, this hurts. If only Move Through Cover helped here...
At the same time, RCL does give units a lot more threat potential. A walking Tyrant can assault 18", scary. It will all be about trying to control the randomness, set up long charges from a safe position (i.e. say a 10" charge from area terrain). If it fails, you're as safe as you want to be (i.e. cover) and you can move up next turn to get a shorter charge range. If you succeed, well take advantage of your unexpected gains. What you don't want to be doing (and what your opponent will be trying to do) is trying to charge 8"+ and being in the open. You can pre-measure - make sure you're charging safely.
Oh ya, Feed units get rage outside of Synapse which is now +2 attacks. It's nice now that when your Synapse dies, your guys can get better in some ways.
Also, all those MCs come with standard AP2 in combat. And they strike at initiative, something which is very rare now in other armies (generally AP2 weapons are unwieldy). Add in Smash attacks for those weaker MCs like Harpies and Tervigons and they can still reliably drop vehicles in combat.
Relationship with shooting - Cover is much, much easier to get. The really big MCs like Trygons, Mawlocs, Tervigons & Tyrannofexes should always have a 5+ now. Even area terrain automatically grants them a cover save, fan-friggintastic. It's not the 4+ of old, and with careful positioning, your whole army could have gotten it, but there should be no quibbling now from your opponent and it's easier for your army to spread out. Mass missiles/lascannons can still be an issue though so don't think you're suddenly scot free. FNP though is much more likely to go off, especially on the big guys so in essence against Lascannons, you're better off than before (previously you got a 4+, now you get a 5+ followed by another 5++). Night Fight can also be of a big assistance in the early turns though most armies have an answer to this regardless.
Although cover is more useful for the bigger bugs, it's far less useful for the little guys. They are much more likely to get removed from play very quickly, particularly with options like focused fire and the general reduction in cover saves to a 5+. It's easier to get cover for units at least but conga-lining from cover into the open isn't as safe as it used to be.
Tyranid shooting as well got a boost against other horde armies. Simple weight of fire enjoys not having to deal with mass 4+ cover saves but rather 5+. It doesn't really matter against Marines unless the Pyrovore (lol) or Zoanthropes come out to play but everything else is more susceptible. Blasts always getting their full strength helps with the light-medium strength blasts Tyranids have available as well - not likely to drop a tank but they can shave off hull points here and there.
Shooting now takes down the closest units and combine with overwatch, this can leave Tyranids more regularly out of assault ranges by taking out their closest models and the opponents. Remember the adage against Space Marines? Don't shoot them if you want to assault them. The same goes now pretty much against all armies - those extra couple dead bodies could leave you high and dry and you don't want that. Overwatch isn't a huge thing though it can cause one or two extra deaths, particularly against Termagants and it will occasionally leave you failing a charge - just remember to try and be in advantageous position if this happens.
Miscellaneous -
Psychic Powers: remember the old psychic choirs? Tyranids can have a ton of psychic models out there and what's even better, there are more psychic powers to choose from and lots of options which can take the randomness factor without losing much. Tervigons are obviously wanting to keep their Catalyst power - you don't want to risk losing it on the Biomancy table for something like Haemorrhage. Broodlords though? Roll away. Hive Tyrants? You lose Paroxysm but the entire table outside of Haemorrhage and the Primaris power are pretty solid. Biomancy and Telepathy are pretty solid tables on which to roll for such models and being able to grab several options in HQ and Troops means you'll be getting some good powers. Telekinesis is decent enough too though with a bit less application.
Also, from the worst psychic defense, to the 3rd best. It's still mediocre until you get up close and personal and Runes of Warding + Runic Staves crap all over Shadow in the Warp, but the nerf to Psychic Hoods means it's better relatively than it was before. Every bonus you can get, take.
Reserves: Null deployment is gone, I was never a huge fan of using such armies so personally not a huge loss but the loss of options is never a good thing so negative there. The ability to take advantage of poor deployments with units assaulting from outflanking is also annoying but if you were doing this consistently, your opponent's needed to improve. It was a nice thing to take advantage of occasionally, particularly with a Tervgion (Hive Commander) and that's really it. You can still use outflanking to pressure the opponent but it's no longer immediate pressure. Otherwise, reserves are still a decent option. Zoanthropes, Devgants, Hormagaunts, etc. in Spores or Trygons/Raveners underground all work that little bit better now to support a normally deployed army - with or without Hive Commander.
Flying MCs: Particularly Flyrants, these add some huge mobility and offensive bonuses to Tyranid armies. Although they don't have a skyfire option against flyers (please?), vector strikes + normal weapon loadouts + being able to land and start munching little mens on the ground is a great combination. They aren't as durable as normal flyers (being able to fall out of the sky 33% of the time, every time a unit hits them) but without mass anti-air options out there yet, certainly a nifty tool to bring. Add in some Biomancy for Flyrants who are not toughness 9...
Allies: There are none. Ouch. This really is a big kicker and we can see where a lot of Imperial whining comes from, they can ally with nearly everyone. At least being able to ally with certain options like Dark Eldar, Chaos or Daemons could make vague sense. I mean, there are some crazy stretches out there and anything with Tyranids would be just as crazy. Simply being able to access flyers or meltaweapons would be massive.
Fortifications: They can't shoot the guns but when a brood of Devilgants sits inside and blasts away? And Hive Guard hide behind it? Ya, they may not get maximum use out of them but they sure do get some use out of them.
USRs: Preferred enemy is now on shooting, close combat and to wounds. Pretty awesome improvement. It's not as good as improving one aspect as it used to be but it will be helping you out more consistently across a game. Chuck in the improvement to poison (my Trygon is no longer wounding you on 4's with re-rolls but 2's with re-rolls? sweet) and Tyranids gained some improvements there. Fleet is an overall reduction in capacity to assault but it does make those random charges more reliable so Genestealers, Raveners, Hormagaunts, etc. are all very happy.
Extra FoC: Remember everyone complaining about the cramped nature of the Elites slot for Tyranids? Have three more at 2000 points. Every army gets this but it was a major flaw of many Xenos books that one of their special slots was crammed. Now you have an option to cram it with twice as many units at higher points.
Objective Focused Missions: these were the norm now but there seems to be an increased emphasis on them and mobility in general for 6th edition. Tyranids excelled at this and still do (though dropping Termagants and going to ground whilst in Synapse range is no longer viable). Tervigons creating more scoring units is still the go-to method for doing well here and with the reduction in tank effectiveness and increase in Fearless unit effectiveness, removing Tyranids from objectives is no longer as easy as it would seem.
Conclusions
Tyranids look like they've improved though the staples of Hive Guard and Tervigons look to be...well staples still. I wouldn't be surprised at less foot MCs as AP2 weapons become more popular (though with FNP up, MCs are ahead in this department across editions) though with flying MCs the total number might remain the same. As ever with the Hive Mind, evolution and adaptation are paramount. Time will tell what the end product is.
