Hooray for Tyranid stuff.
You have a lot of cool ideas in here, but I feel some of the rules could be polished up, and some of the pricing seems really off.
For starters, you're probably spending a ton of time and energy rewriting and tweaking those wargear lists each time. I recommend breaking the various wargear options up into armory categories (dakka biomorphs, melee biomorphs, special biomorphs, tail biomorphs, etc.) and then listing three prices for each biomorph. The first price being the cost for a single wound non-
MC, the second being the cost for a multi-wound non-
MC, and the third being the cost for an
MC. That way, you can adjust the cost of a biomorph based on the model's power and survivability without having to tweak each one for every individual unit. You can just say, "this unit has access to X, Y, and Z armories."
On a related note, many of your pieces of wargear seemed ridiculously pricey for some units. Charging 5 points per hormagaunt to give it a 6+ invul save with a synaptic shield? Ouch!
Jumping over to the special rules...
Shadow in the Warp: The thing about
SitW is that it's supposed to be the tyranids' psyker defense that works by shutting down their casting. What's more, it's meant to be some of the scariest psyker defense in the game. The leadership thing is a leftover from the days when psychic powers worked off of leadership. Making it affect non-psykers is nice for fear and psychic shriek, but those are relatively niche applications that don't really match its fluff or intended awesomeness. My personal fix for
SitW? Psykers take a -1 to all psychic tests (normally harnessing the warp on a 5+ instead of a 4+). Keeping the leadership debuff is reasonable and fluffy though.
Synapse:
ATSKNF is really meant to be a special snowflake marine rule. I'm guessing you wanted to represent the swarm being able to behave in a reasonable, tactical fashion, but I'm not a fan of swiping someone else's special stuff. Plus, Fearless works perfectly well most of the time.
BIOMORPHS
Lash Whips: I don't like that entangling is a random d3. It's another die roll to remember, plus it requires you pause and recalculate things. A
WS penalty is a neat option to have access to, but I'd probably prefer to the higher initiative most of the time. These are minor nitpicks.
Crushing Claws: I like these changes.
Bludgeoning Fist: I also like this. Sort of a tyranid power maul.
Lancing Spear: Sure, though this "power weapon but not" thing is starting to feel slightly un-tyranidly.
Axe Claws: See above. Part of the fun of playing aliens from outside the galaxy is feeling distinct from other factions.
Biting Tendrils: I like these a lot! Fluffy, cool, and useful.
Shocking pseudopods: These seem perhaps a bit too good when you get your full number of attacks with them. A couple hormagaunts could reliably wrecks most vehicles with these. Consider restricting them to one attack per model (making them grenades basically) or having the haywire only kick in on a 6 or something.
Amorphous Pseudopods: This one gets complicated in the wrong situations. It triggers on a succesful hit, but its purpose is to inflict extra wounds. So you would need to keep track of successful hits that wound and that don't wound separately and resolve them separately in case you're fighting multi-wound models or models with a better save. Maybe have this trigger after a wound goes unsaved instead? Or take a page from the eldar book and have it wound against initiative rather than toughness?
Toxin Spike VS Barbed Stinger: Tails are pretty much only an
MC thing right?
MCs will wound most non-
MCs on a 2 already. Even when they don't wound on 2s, they're wounding anything T5 on 3s and usually rerolling if they have any sort of poison. Therefore, the Toxin Spike and Barbed Stinger are mostly useful as a source of an extra poison attack. Therefore these tail options are mostly useful against
MCs (because those are the things affected by poison that the
MCs aren't already wounding on 2s).
MCs already have
AP 2, so the difference in tail
AP is moot. Even if tail attacks weren't AP2, the difference between AP5 and AP6 is mostly moot when you're using these tails against their main target:
MCs. Some enemy
MCs will be toughness 7 or 8 or even higher, which the Barbed Stinger only wounds on a 4+ while the Toxin Spike wounds on a 2+. This is my very long-winded way of saying that I see no reason to ever take a barbed stinger over a toxin spike. What is the barbed stinger's niche?
Toxic Miasma: Ouch. This would be okay against marines, but now it means that Malanthropes and Venomthropes that survive a single round against orks or gaunt swarms will now basically kill off 2/3rds of all orks still in the combat. This seems way too good in fairly common situations.
Mucous trail: Seems fine. Have you considered rewriting it to simply be defensive grenades? Technically, this gives you a blinding shooting attack (at strength 1), but I'm not sure that's a bad thing. Then you could field slimy slug
MC's!
Synaptic Shield: Neat!
Thickened Carapace: Yes please! Though ironically, this may make
MC's *less* durable in some games as common forms of anti-
MC (rending, plasma, melta, lascannons, etc.) already ignore their 3+, and grav weapons will now be more effective. I still like having the options.
Occular Spectrum: Nifty!
UNITS
Hive Tyrant: Master of Biomorphs is a neat rule, but I'm having a little trouble picturing the situation in which you would use it. If I already have some sort of strength enhancing biomorph, won't I usually just use that anyway? After all, the tyrant is already AP2 and,
iirc, ignores unwieldy by virtue of being an
MC. He also doesn't have much need for most unwiedly weapons because he's AP2 innatley. So he could just take bludgeoning fists or whatever and avoid taking things like axe claws all together. What would be the scenario in which I would use this special rule? I'm not knocking it. This rule sounds like it should let me do something awesome. I'm just not sure what that something is. D:
Warriors: If I give warriors wings, don't I basically eliminate the niche of shrikes? Or are these meant to be the new version of shrikes? Shrikes have a worse save but are otherwise just warriors with wings.)
Genestealers: I'm afraid having more options for expensive gear really doesn't do anything to fix this popular-but-underpowered unit. The broodlord can take some neat options, but taking expensive upgrades just makes genestealers even more expensive when they die. Genestealers suffer from being too expensive for their survivaiblity already, lacking assault grenades, and having upgrades that are extremely expensive when applied to a whole unit. I don't think your changes really fix any of these issues. :(
Gaunts: Same criticisms as warriors and genestealers. Wings make them redundant with their fast attack counterparts. If that's intentional, no worries. The upgrades are probably too expensive for what they do in many cases. Mixing and matching certain upgrades (mucous trail) is useful and reasonable for the points cost, but tracking a bunch of individual upgrades as you remove models seems like a pain. Gaunts are meant to be swarms of mostly-identical critters. I feel your rules encourage a weird sort of "specialist gaunt squad" where you have cheap bodies up front, mucous trails in the back, and a handful of slightly upgraded guys in the middle to do damage. Which is a lot of micromanagement for the default spammable bodies of the swarm.
Zoanthropes: Their invul saves got weaker under these rules, but no other criticisms here.
Venomthropes look fine.
I hope all that is readable. It's late here, and I've had a full day. XD
