Mecha Weapon Systems sound pretty cool fluffwise, but computers start getting pretty glitchy when you add way more code than needed for their processes.
If you're taking Implant Attacks namely for Demon Princes, I have a feeling any halfway intelligent player will render them useless. If you're facing Demon Princes, I'd expect them to be Lash Whip princes. He has a 24" range with Lash of Submission, combined with 12" movement phase due to wings. With a 36" potential threat range, he can then place you
2d6 wherever he wants. You have to be 18" or better to him to shoot, much less have a chance at assault. Pushing your Tyrant out of firing range is pretty easy to do, or pulling you into plasma rapid-fire range of his Plague Marines and assault range for the Prince itself is pretty easy. If the rapid-firing plasma doesn't kill your Tyrant, the assault from the Prince will finish it off since it has a higher initiative and ignores armor saves. He gets a 4+ invul save against your assault, so your Tyrant is at a severe disadvantage in every way. The best way to deal with Princes is to overload them with saving throws. They're like killing four Marines, just shoot it over and over, preferably with two Devourer 'Fexes.
As far as your "single minded" intentions, that's what you have your main Tyrant, the flying assault machine, for. Your second Tyrant is for support. People who bring a Devourer Tyrant for a single-minded purpose also give it wings, and that purpose is to harass enemy troop flanks. They don't go after big things like other Monstrous Creatures in assault. Overwhelming things with the 12 shots is what wins against other
MCs. The problem with this on the walker is the lack of range combined with lack of mobility. The wings also let it get into assaults with tanks fairly quickly, where having S6 isn't that big a deal since now when you assault a tank, it's always against back armor and you get your
2d6 for Monstrous penetration. But, again, this is for a winged Tyrant, since it relies very heavily on mobility. Run only lets you possibly get into range on the second turn, instead of the third. Afterwards, your opponent will simply move away from your Tyrant, or in the case of the Lash Prince move you wherever he wants you. If they do move away, you're probably going to be wasting shooting phases chasing after them. Worse case scenario, he baits you into chasing him a bit simply to step forward into rapid-fire range. This goes for any army with guns.
Furthermore, any highly mobile army will just walk away from your Tyrant. A Tau Fire Warrior gunline can decimate your Tyrant before it even gets in range, as can any vehicle in the game. Point being, for sacrificing three S5 shots a round, you get double the range, S8 triple shot that can kill off transports and skimmers with relative ease. Play test both ways against suitable opponents, see which you like more. As far as the added point cost, the removal of assault biomorphs from your sniperfexes should pay for it (more on that later). Oh, and unless you're doing Psychic Choir, don't really need to bother with a Psychic power for your walking Tyrant.
ANYHOW, moving on from the Tyrant and on to your Sniperfexes...
The further reason not to mess with the close-combat biomorphs is further understanding of the assault phase, namely how power fists work. They always strike last. It says quite explicitly,
always strikes last. It's not "swings at I1," which you'd still be better than with your I2. Yes, this does mean your Fex will hit first. Will it kill the squad that just charged you, thus letting you kill the power fist before it hits your 'Fex? No. Your Carnifex gets two attacks at WS4. Against anything that could possibly want to chase down and assault your 'Fex (Assault Marines, Orks, Genestealers, Bloodletters), you will miss your target 50% of the time (4+ to hit), and fail to wound it one out of six tries. Take note, this is no difference from being at WS3. You still have to roll a 4+ to hit. Whatever you hit will be dead, yes, but you will not kill the powerfist holder, you will kill a random marine/ork.
Even further, though, is the small chance that people will actually assault your Sniperfex. You should have them positioned at range as a distant object. Your Devourer 'Fexes are right in their face, though, giving them eight S6 twin-linked re-roll wounds shots each. Those will be the assault targets long before your Snipers will. The only thing that would chase your Sniper first is perhaps infiltrating Genestealers coming from a flank or from behind and looking for a big target, and your
WS/I upgrade won't do a thing but make it an even bigger point flush. The spine banks you can model all you like, there's no rule that says "If you have a custom modeling it must do something!" You can keep your miniguns as you like, it sounds pretty awesome, but don't pay for a useless upgrade.
Long story short, the extra Initiative and
WS point will never, ever do anything for your 'fex. Nor will the Spine Banks, for that matter. It just takes up points.
I would not remove your Zoanthrope if you intend to keep Gaunts, you will need them for Synapse, and you will need troops to claim objectives. You cannot win two of the three missions in 5th if you cannot claim objectives. You could lessen their number by one, bring two Synapse Zoanthropes, both dedicated to moving the Gaunts as need be. Once you get them there, you can use a fun little tactic to keep them there for a very long time. You put the gaunts around the objective you're wanting to hold, and have them go to the ground. I can't imagine anyone not putting an objective in terrain, so you already had a 4+ cover save. Add in going to the ground, you get a 3+. Then, move your Zoanthrope away from the Gaunts, causing them to Lurk. This gives them a 2+ cover save. A ring of Gaunts, all with a 2+ cover save is very, very difficult to uproot. Ask anyone who has tried to shoot Pathfinders out of their hiding spots. Things to beware of with this tactic: flamer templates, units within assault range, and Lurking broods cannot score. This means you take target priority on all flamers and assault specialists heading their direction. It also means you need to move your Zoanthrope to the Gaunts just before the game ends so you can claim that objective. Remember, lurking does not mean you don't have control, it means they cannot move but can shoot as normal. Instead of shooting, though, you'll be enjoying your cement hold on the objective while the rest of your army decimates the opponent.
You also need to keep those guardian Zoanthrope alive. You only have four synapse creatures, but if played smartly that's plenty. Keep that third Zoanthrope if you feel four is too few. While your gaunts are lurking with their 2+ save, your Zoanthrope should also be getting into cover and going to the ground for a 3+ cover save in addition to their 2+ armor. With your list, you shouldn't have too much trouble giving the opponent more dangerous targets than a Zoanthrope and Gaunts who are a pain to kill.
This tactic does mean that you don't get your Psychic Choir, but in all honesty that is a very gimicky tactic. It works great against armies people don't tend to play, and you'd slaughter anyways: Non-Skimmer Eldar, Tau, Dark Eldar, etc. Marines are basically fearless, Grey Knights are fearless, many Chaos Marines are fearless, Demon Princes are fearless, Orks have mob rule leadership so are fearless 90% of the time. Furthermore, Psychic Choir is used to force Sweeping Advances and prevent people from assaulting your Hive Tyrants due to their Horror ability. If you keep all of your assault units (Genestealers, flyrant) all near each other, then you're just asking for a barrage of templates. Very few people want to assault a Flyrant, anyways, so the Horror rarely comes into effect.
Lastly, your troop line is still way too small, even if you add two groups of nine. Nine gaunts fit under large blast templates very well. You need to up their numbers closer to 14-15 range. Same with the Genestealers: a single six-man squad won't accomplish much other than eat a blast template and be wiped off the board. I'd get these guys to at least eight, and preferably two groups of them. Drop the carapace to make room for the points. As I said before, just play smart and you can get 4+ cover saves fairly easily by having a gaunt screen, an enemy model screen, or using terrain appropriately. Remember, it's better to survive a round in cover than it is to fall short of assault range and be a sitting duck.
Too long, did not read:
-You really should have a Venom Cannon with Strength upgrade on your walking Tyrant, with only two Sniperfexes your list needs more long range firepower. Gun Tyrants aren't for assaulting, they're for shooting, and a Venom Cannon is far better than three more Devourer shots.
-The
WS and Initiative upgrades will never, ever help your Carnifex in assault on the very rare chance they get assaulted. People will assault pretty much everything else in your army long before they'd run across the board to get to your Snipers.
-You need to boost your troop count. The models per squad is too low to survive long enough to score objectives for you.
Good lord, didn't mean to write that much. Anyhow, hope it helps. The best way to see all of what I said, though, is to playtest it. You don't need the models, my friends and I use shreds of paper for troops, calculators for tanks, solo cups for drop pods, whatever we have available to playtest our lists before we invest in the models.
Can this list cut it in theory?? I'm terribly short on troops, but that isn't really going to change very soon. I've also dropped some "free" killpoint units that would be fun to build later, such as individual raveners...
