OK all,
The new codex is here, and my opinion of everything we've heard so far has been pretty clear, but as I have said numerous times, Hypotheses are made to be challenged, changed and broken. What follows is My thoughts on the codex, not the presentation (which beyond a few pictures that looks really funnily stupid) is fantastic, but the rules, the crunch the part of the game that lets you use those beautiful models we've bought and spent hours converting and painting.
I'm going to try to refrain from comparing this codex to the last one, the last one was terrible (baring a brief bright spot at the end with the advent of 6th ed) we all know that but this is what we have now so lets dive into the deep end and learn to swim.
Army Wide Special Rules:
Instinctive Behaviour: One of the rules that literally defines a Tyranid army, You know it you love it and you probably hate it as a nid player (which is kinda the point). So the basis of how it works is that at the start of every turn any Tyranid units without at least 1 model within synapse range of a synapse creature must take a leadership test, if the test is failed you roll on a separate chart which tells you how your Tyranid creature reacts to the situation it finds itself in without the overbearing will of the hive mind.
Tactical considerations: Given the low leadership of most Tyranid units, which typically ranges mostly between 6 and 8 for non synapse creatures. It is very important to ensure that any army has a robust synapse web. Stay away from big lynchpin creatures that try to hold the whole army together by themselves, All they are doing is waving a big "shoot me first" sign over their heads. Instead Look to have overlapping fields of synapse so that if you lose a unit you don't madly have to re-arrange your army so that its back in control. Look to units such as Zoanthropes that serve dual purposes as gun batteries, support and synapse to really add that extra layer to your web.
Another tactic is to string out your units, only one model in a unit needs to be within synapse range and while risky is therefore possible to drag your units out over a wide area in order to maintain control. Kind of like bellow
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While it is dangerous as it allows mobile enemies to manoeuvre and kill lynchpin models it helps us apply board control and force those dangerous decisions concerning target priority on our opponents.
As to the tables themselves: They can broadly be designated as the "Defensive" the "Shooty" and the "Stabby" lists, the first result covering the rolls of 1-3 is usually debilitating, it's a bad thing, hope it doesn't happen, units either fall back, go to ground or eat themselves. This is worst on the assault units that actually do try and kill themselves about half the time they fail an IB roll, therefore it is even more important to ensure that you have a secure forward synapse net to hold the little bugs in line.
the second set of results (4-5) is pretty much the same as last edition, the unit either runs to terrain and is not allowed to shoot unless inside it, shoots at the closest visible enemy unit (So don't let those biovores and Hive guard out of synapse as they are not allowed to fire upon units they cannot see) and finally Feeding units must attempt to charge the closest visible enemy unit. These results aren't so bad but remember they will happen less often than the "bad" ones and more often than the ostensibly "good" results, it's wrong to think of these as the default results because they are in the middle of the table so don't do it.
And finally on a 6 we get the "benefits" of IB, Mechanically they operate like the 4-5 results but have a few special advantages that make life a little easier for the bug that rolls them. Namely Stealth, Preferred enemy and Rage.
While it is tempting to think of the hilarity that ensues when your opponent kills a synapse creature only to find your units MORE effective, dont! It's a bad idea, Instinct behaviour is bad so make sure you have synapse at all times.
Also, if you're running disruption units or units designed to range ahead of your main force your going to need extra fast synapse to accompany it as most of our "vanguard" organisms now have instinctive behaviour (see lictor)
Synapse: yeah its pretty good.
Nah, synapse is the off set to IB, its what makes a nid army tick. What does it do? gives fearless and auto-rally
Now while that doesn't sound huge it means that nids in synapse range probably give the least amount of proverbial things about moral, even more so than marines. "but what about terrify" I hear you say, well yeah terrify is still rough on us, I'll pay that, but the auto-rally in synapse that appears initially redundant (fearless gives auto-rally) is I believe specifically there to protect us from terrify, as while the unit may not get the benefit of fearless when terrified it still does not continue to run while under synapse.
So all good.
As to the other benefits of synapse, there aren't a lot of armies that can kill multiple units of 30 gants or gaunts in combat, not because gants and gaunts are hard to kill, but because they have to kill EVERY SINGLE ONE of the flippin little things.
So Synapse good!
Shadow in the Warp:
A 12 bubble of aggressive psychic defence. In an age where almost all psychic defence has become passive and force multiplying blessings are the really valuable parts of the psychic disciplines (see 2++ rerollable saves) being able to drop the casting potential of any psyker in the game to around 50% at best is fantastic. It is a shame that the radius for shadow is not intrinsically linked with the synapse special rule as then the army would be able to achieve some extremely strong anti-psycker combos with the Norn Crown, primaris and warlord traits.
Therefore we have probably 2 ways of really using this power, the first is to merely rely on it once the swarm hits home, to protect you from force weapons, maledictions and witch fires allowing you to largely ignore these powers (50% cast and still get DtW). While this is appropriate it is perhaps not the most interesting and efficient use of this rule, the other way to use it is to implement a fast mobile and dangerous synapse creature of your own (re: Flyrant) to hunt down enemy psykers, preventing them from casting the truly game changing powers like the divination tree or the eldar seer powers, and then crushing them with your tyrant.
Oh and NB: Despite the quick reference chart at the back of the book the full text for the rule means that no, shadow does NOT stack for each synapse creature.
edit: a Secondary note on shadow, the leadership de-buff is not just for psychic checks it is for all leadership test, this doesn't mean much for most support psykers who are usually hiding in squads and then therefore using the squad leadership for non psychic checks. But for units like Daemon princes's and fateweaver, it can be brutal, it is also another knife this army puts into seercouncils as they are all psykers they all take the Ld drop to their other tests.
So, Shadow good.
Next chapter (Warlord traits and Relics)