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This might have been done before, but I'm curious to see the likelihood of a wrecked result for a Tyrannofex shooting a rupture cannon at AV14 out of cover. I might do AV13 and AV12, too. We'll see.

A caveat: I am not good at statistics. I will use good, old-fashioned, middle-school probability trees. It's more work, but it's accurate, unlike lazy mathhammer that says each T-fex hits exactly once each round. I'm going to show all my work, so if some math teacher wants to go through and check it, they can.

Alright, here we go. I'll be more explicit in the first step, then use more shorthand when I get rolling.

HITTING
A T-fex gets two shots at BS3.
1/4 of the time, it will miss both shots. (1/2 chance shot 1 misses x 1/2 chance shot 2 misses)
1/2 of the time, it will hit exactly once. ((1/2 chance shot 1 misses x 1/2 chance shot 2 hits) + (1/2 chance shot 1 hits x 1/2 chance shot 2 misses)
1/4 of the time, it will hit twice. (1/2 chance shot 1 hits x 1/2 chance shot 2 hits)

PENETRATING AND WRECKING FOR EXACTLY 1 HIT
Shot penetrates 1/3 of the time.
Penetrating hit gets wrecked result 1/3 of the time.
1/3 x 1/3 = 1/9.
1/9 x 1/2(prob. of exactly one hit) = 1/18.

Chance of wrecking for one hit = 1/18

PENETRATING AND WRECKING FOR 2 HITS
4/9 chance that both fail to pen.
4/9 chance that exactly one pens.
1/9 chance that both pen.
If exactly 1 pen: wrecks 1/3 of the time.
Prob. of one pen and one wreck = 4/9 x 1/3 = 4/27 = 12/81.
If both pen:
4/9 chance that both fail to wreck.
5/9 chance that AT LEAST one wrecks.
Prob. of two pens and AT LEAST one wreck = 1/9 x 5/9 = 5/81.

Chance of wrecking for two hits = 17/81.

Chance of 2 hits x chance of wrecking for 2 hits = 17/324

Total chance of wrecking AV 14: 1/18 + 17/324 = 35/324

That's 1/9 - 1/324, so the chance of wrecking AV 14 with a T-fex in one round is just under 1/9.



I'll do AV 13, too, since it won't take as long, but I'll use more shorthand.

Same hit %.

1 Hit
Pen: 1/2.
Wrecked: 1/3.
Total chance w/ 1 hit = 1/6.
Total chance of 1 hit and 1 wrecked = 1/12.

2 Hits
1 Pen: 1/2.
2 Pens: 1/4.
Wrecked (1 pen): 1/6 = 6/36.
Wrecked (2 pens): 5/9 x 1/4 = 5/36.
Total chance of wrecked for 2 hits: 11/36.
Total chance of 2 hits and wrecked: 11/144.

Total chance of wrecking AV 13 = 1/12 + 11/144 = 23/144

That's 1/6 - 1/144, so the chance of wrecking AV 13 with a T-Fex in one round is just under 1/6.


Oh, what the hell. I'll do AV 12, too.

Same hit %.

1 hit
Pen: 2/3.
Wrecked: 1/3.
Chance for wrecked on 1 hit: 2/9.
Chance for 1 hit and 1 wrecked= 1/2 x 2/9 = 1/9.

2 hits
1 Pen: 4/9.
2 Pens: 4/9.
(Interesting...)
Chance of 1 pen and wrecked: 1/3 x 4/9 = 4/27 = 12/81.
Chance of 2 pens and wrecked: 5/9 x 4/9 = 20/81.
If 2 hits, chance of wrecked = 32/81.
Chance of 2 hits and wrecked = 1/4 x 32/81 = 8/81.

Total chance of wrecking AV 12 = 1/9 + 8/81 = 17/81.

That's 2/9 - 1/81, so the chance of wrecking AV 12 with a T-fex in one round is just under 2/9.


That is...not as good as I'd hoped...

T-fexs' are officially overrated, do one for AV10 to see the chance of them wrecking my trukks, I'm too lazy to use math outside of school

*Sigh* fine.

Same hit %.
Every hit pens.
Since it's open-topped, each pen has 1/2 chance to wreck.
1/2 chance for exactly 1 hit x 1/2 chance to wreck = 1/4.

2 hits = 2 pens.
1/2 wreck once.
1/4 wreck twice.
3/4 wreck.
1/2 chance for 2 hits x 3/4 chance to wreck = 3/8.

Chance to wreck: 5/8.

Of course, with Trukks you're happy with anything but weapon destroyed. With 1 hit, you're unhappy 1/6 of the time. With 2, you're never unhappy (2 weapon destroyed = immobilized). So against Trukks, a T-fex will get a bad result (2 misses or just weapon destroyed) 1/4 + (1/2 x 1/6) = 4/12 = 1/3 of the time.

So chance to get a good result = 2/3.

Thanks for this math! The ork truck equasion also doubles as dark eldar raiders for the most part, so what I take from this is that if you have 3 t-fexes, you can put down ~2 raiders in a turn. With 6 wounds, it's about 10 dark lances to kill a tfex, and considering that most dark eldar armies have ~20 dark lances, the tfex wont go very far against the deldar raider spam armies.

T-fex chance to wreck:


Armor...Probability of "Wrecked" result on Vehicle damage chart
14........10.8%
13........16.0%
12........21.0%
11........25.9%
10........30.5%

Honestly, I'd rather not use him. The lack of AP1 just kills it for me.

Of course, he is a T6 model with 6 wounds and a 2+ armor save. He does have his uses, but I think tank-busting from range is just an option thrown in with no real idea of how effective it will be. Now, imagine him with Acid Spray and Dessicator Larvae vs. a GEQ army sitting (contesting, but not capturing obviously) a back objective.

I feel a T-Fex' worth goes a little beyond the raw numbers he produces. His use is more "Look at me! I'm a huge monstrous, nigh invincible creature sitting at the back of the board in cover, spitting S10 shots at you! Do something about me!".

Whether he's actually any good at wrecking vehicles is a different point entirely, he's scare factor, and makes your opponent divert large amounts of resources to take him out. Resources that are then not pointing at your more squishy elements.

GCMandrake wrote:I feel a T-Fex' worth goes a little beyond the raw numbers he produces. His use is more "Look at me! I'm a huge monstrous, nigh invincible creature sitting at the back of the board in cover, spitting S10 shots at you! Do something about me!".

That is the case with many things, isn't it?

Still, a very good point!

Now if the Tyrannofex was actually nigh-invincible creature that would be true, but as the math shows those S10 shots aren't doing much, and the Tyrannofex itself can be put down with sniper fire.

In the spirit of GCMandarakes post, I find it interesting that most math and tactics (with a single notable exception) sees the T-fex as being essential a Rupture Cannon.

While I agree that it is an interesting weapon, I believe it is sometimes overlooked that the T-fex carries three separate weapons on what is a very survivable monstrous creature frame.

Also the redundancy in saying that a 265 point Rupture Cannon isn't worth its points should be obvious.

The T-Fex costs more than 3 zoenthropes in a myconic spore.

Math hammer will be very unkind if you compare 2 BS3 Str 10 hits with 3 BS4 Str 10 AP1 lance hits.

Even against an ork truk the zoenthropes are better.

The only real advantage a T fex has is it's heavy support instead of elite, and the new nids can quickly use up all 3 of their elites choices.

Yes, but the Tfex fires on round 1, while the Spods are in space, and on round 2 (along with the zoey's), and on round 3, when the Zoey's are killed by a powerfist charge from the wreckage of whatever they shot at.

Look at Hes' math again. Tfex has a 2/9 chance of popping a land Raider. So it's got a 7/9 chance of living through. If it wants to let it's guys charge it needs to live through 2 rounds, right? so 49/81. Getting a little dicier.

Further, he's counted immobilize as a bad result. For my money, immobilizing a Land Raider is satisfactory (it'll get eaten up once it stops moving, and it can't surgically deliver the assault terminators/command squad/whatever. So it's odds are a bit better because of that.

Yeah, the T-fex is clearly not about raw, single-turn hitting power. It's about getting 12 shots a game, because a T6 2+ Sv creature isn't gonna die.

That said, based on the math I'm thinking you need a unit of Zoanthropes, too, because the T-fex isn't good at stopping a Land Raider early, which is when you need it.

And 40kenthusiast, you're pretty much on the money, except for one thing: T-fex has just under a 1/9 chance of popping a Land Raider. My math includes the 2 shots. If you include immobilized and stunned as "good" results, though, it's 2/9.

40K hit one one very important different between the TFex and Zo's, and I'll expand on that.

Zoey's are pretty much sacrificial. Even with their invulnerable save, they don't have much of a toughness, and the short range of their weaponry leaves them vulnerable to immediate eradication on the turn following their arrival, if you use the Spod. If you don't use the Spod, odds are the Zoey's will be shot off the board before they ever get into range.

Secondly, the Zoey attack is psychic, and can be shut down by any of the other anti-psycher stuff out there. Try re-running the effectiveness of the Zoanthropes' AP 1 shot when fired in range of a Hood, Runic Weapon, Runes of Warding, etc. It's funny that when everyone talks about the effectiveness of the Zoey's shooting attack, they seem to forget the fact that it is a psychic power with all of their inherent limitations.

Saldiven:

I think that's why it's got all the bells and whistles (S10, AP1, Lance, etc) to make up for its unreliability in the face of psychic defense (and Perils of the Warp).

But I was thinking. Hesperus, can you crunch us some numbers for Deathspitters and Venom Cannons on Rhinos and Chimeras?

It's funny that when everyone talks about the effectiveness of the Zoey's shooting attack, they seem to forget the fact that it is a psychic power with all of their inherent limitations.

Well, historically it's not that funny, but as time goes by, I think it will increase in humorousness.

The fact is, in the past people have had little to no focus on nullifying psychic attacks. I played many games with my Nids under the previous Codex, and not once did anybody even have a model on the board that could stop their shooting. Of course, I think my average roll to hit with their focused blasts was about 1.0001, but whatever.

Going forward, my impression is that GW intends to put more powerful psychic options in lists, as well as more ways to shut them down. On some level I appreciate the idea of another dimension like that, but I don't appreciate it leading to stupid, poorly balanced powers like JOTWOWW.

I much prefer the look of the Warp Lance (or whatever they call it) where it's more a case of an overpowered, but still generally reasonable shooting attack. S10AP1 is strong. Add in Lance and it's too much. Factor in that it can be nullified, and it's reasonable.

Regarding the T-Fex: I think it's a mistake to focus too much on the shooting stats. It's true this is a model that's relatively mediocre when trying to blow away tanks. It's also extremely good at not dying, and has nice flexible firepower, which can be used on the move. It's also pretty tough in CC.

On its face, the price tag does seem too high, I agree. In a vacuum, it probably is overcosted. In the context of the Nid list, tho, I think it's a pretty "backbone" sort of unit. The Tervigon provides a nice big chunk of way undercosted superGants, that it allows you to balance them out with an overcosted T-Fex and still field a workable. list.

can you crunch us some numbers for Deathspitters and Venom Cannons on Rhinos and Chimeras?

Speaking of Deathspitters, I'm seeing a handfull of options for delivering S5AP5 shots at the rear armor of vehicles. To me, that's a useful and overlooked option for the Nids to deal with light vehicles. Everyone goes right to Hive Guard, but they strike me as a bit overrated for what they can do. By comparison you can drop Warriors in Spods, or Trygon Primes, and they'll have such a volume of S5AP5 shots on AV10 that one can expect some decent results.

While I appreciate the analysis, WAY too many people are thinking that the space for a T-fex is "in the back".

It is a strength 6 monstrous creature with 6 T6 wounds and a 2+ save, it has a strength 5 large blast shot and a flamer template, and can fire those two plus the rupture cannon.

If you are worried about losing it to a charge, screen it with a thin line of gants, but otherwise, this guy is a front-liner. Run him AT people, and then suddenly, the "value" of the rupture cannon becomes more clear. This shot is 'in addition' to a 2+ save MC running across the table, shooting large blasts flaming people and charging all units except dedicated CC units. It is also providing a 4+ cover save to any non-trygon MC that is hanging out behind him.

As I have been discovering, but should have been apparent to us all when we saw the points costs.... Robin has murdered the godzilla nid gunline. If we want to win, we're going to need to milk more out of our units than just 'hang back and shoot'. The T-fex has been very good at multi-tasking for me so far. Get him in the mix, he is clearly not a 'nid hammerhead'.

Again though, with the s5 ap5 massive shot lists, you are stuck using reserve rules to deliver the unit into favorable firing positions. This is worse then just using zoanthropes to do it, as all the issues with podding zoans, save a psychic check, are shared with s5 ap5 options, and while needing a psychic check can indeed be a crutch, at least when the s10 ap1 attack does hit (on a 3+ instead of a 4+ mind you) the s10 hit autopens, where the s5 attack needs to roll a 6.

Thus, s5 massed shooting = fail. If s5 ap5 massed shooting would win games, tau firewarriors would not be so garbage.

If you want shooting outside of the elite slots that can actually accomplish something in a short period of time, the only answer is the upgraded devourers on the fex and tyrant. Sure, ap -- hurts, but 12 s6 shots will get at least 1 pen through on av11, and ~3 pens through on av10. For 190-200 points base the dakka fex and devil tyrant are the best non elite shooting options for light vehicles.

While my math is a bit fuzzier than the excellent maths above, I crunch that with a dakka fex into av10, and counting immobs and stuns as good results, the dakkafex will stop the vehicle 85% of the time with 1 shooting phase, and the thing wont be able to shoot either. You would need 21 bs3 s5 ap5 shots to do the same, or ~15 bs 4 s5 ap5 shots. 21 bs3 shots is a min of, what, 245 points with 7 otherwise naked warriors, or 225 for a naked deathspitter tyranid prime + 4 naked deathspitter warriors?

While I appreciate the analysis, WAY too many people are thinking that the space for a T-fex is "in the back".

Sitting it on the "home" objective seems like a perfectly good option, but that's not for all games, only ones where the enemy has to come to you to win.

A big key with Nids is to keep the pressure on, and try to keep it well distributed so the enemy is dealing with "everything at once." A T-Fex in the back isn't as immediately threatening as one that's up close, screening, shooting, templating, etc. But, as I said above "the back" quickly becomes "the front" if the objectives demand that the enemy move to you.

Luckily for the T-Fex, moving 6" per turn does nothing to reduce his shooting.

Thus, s5 massed shooting = fail. If s5 ap5 massed shooting would win games, tau firewarriors would not be so garbage.

Not a good comparison. We're talking about Tyranid Warriors/Primes and Trygon Primes. These guys generate a lot of S5AP5 shooting, and THEN they're still pretty brutal in CC. They're also appearing behind you. FWs don't have any easy way to get behind things, and even if they did, they'd just get brutalized in CC next turn.

The S5AP5 shooting isn't the reason to take Warriors or Trygons... What it is, is a virtually guaranteed salvo of decent shooting. I find it very questionable to take pure CC troops via Drop Pod. It's far too likely that they do nothing at all. When they can at least unload a lot of shooting, not only does it make them more survivable as they kill potential threats, but it means they can at least do SOMETHING if the enemy elects to focus attention on them.

The S5 is big here, because so much of the rear armor in the world is AV10. Being able to roll a Pen is very important. I'm not saying S5AP5 shooting is great. It's actually rather mediocre. But when you can get a lot for cheap, and drop it behind the enemy, and it's coming from guys that 90% of the universe don't want to CC with, it's nice.

Sure, ap -- hurts, but 12 s6 shots will get at least 1 pen through on av11, and ~3 pens through on av10.

It hurts A LOT. The 5e game is far less about getting results on the damage chart as it is about getting a plusses to rolls on that chart.

It also depends on how you view the results. You're counting stuns and immobs as "good." Not necessarily wrong, but something that skews way in favor of S6AP-.

IMO, these aren't "good" results. When you're putting a unit in harms way like you do with Deep Strike, you want to start things off with a very positive result for you. A stun isn't that, it's like more something you'll take, while your Hammerhead hides behind Disruption Pods to try again next turn.

An Immob result is also pretty subpar in that situation, since, if you're coming from Reserve, chances are it's already done any moving it wants to do. So it's Immobilized. The Devs inside turn around and shoot you with 2x ML, or the Razorback turret hits you with Las/Plas, or whatever, and you aren't really coming out much ahead.

To me, if you're going to Deep Strike, you need to really do some hurt on the turn you arrive. That means a destroyed vehicle, or a badly depleted squad.

Against AV10:
S6AP- : 1/3 Pen, 1/6 Destroy = 1/18 Destroy
S5AP5 : 1/6 Pen, 1/3 Destroy = 1/18 Destroy

So S5AP5 does equally well, and it's something you can get on Troops, which are a very nice thing to have dropping in his backfield. The Warriors also work great with a Prime, and their shooting improves.

To me, the Nid list is a blend of overcosted and undercosted units, and the challenge is to get the right mix. Warriors strike me as a great value, while Fexes seem overcosted.

I'm not sure who I'd rather CC with, point for point, between Warriors+Prime or Dakkafex. At 190 points the Dakkafex isn't cheap, but neither are tooled up Warriors. That's maybe 1 Prime and 2x Warriors. I'll look at the numbers later, but my gut feeling is that the Warriors are a lot scarier to most CC units.

Still your point is well taken, dropping a Dakkafex into the enemy's backfield certainly seems like a reasonable option for a model that's otherwise a bit lackluster. I might have to put the Devourer arms back on one of my Fexes and try it.

"So S5AP5 does equally well"

Sort of, s5ap5 does equally well at just killing av10 on a hit per hit basis. However, a fex will average 9 hits per turn. For s5sp5 stuff to get 9 hits, you need 18 shots, and more points.

Then, there is the issue of av11. s6 ap-- is greater than s5ap5 versus av11.

Consider:

Tyranid Prime, Boneswords, Deathspitter, Toxins
2x Warriors, Boneswords, Deathspitter, Toxins
= 205

vs

Dakkafex
= 190

9x shots at BS4 = 6 hits
12x TL shots at BS3 = 8 hits

The Dakkafex is obviously better.

But, consider CC vs MEqs.

Prime: 4A, 2.67 hits, 2 dead MEq
2x Warriors: 6A, 4 hits, 3 dead MEq
= 5 MEq

Fex: 4A, 2 hits, 1.67 dead MEq

The Warriors are considerably better. They also will strike first/simo, instead of last as the Fex will. And they're Troops, AND they fill your HQ choice with one of the more points efficient HQ options.

They're only T4, vulnerable to Instant Death, and have a 4+ save, but they've also got 9 wounds vs. 4.

Personally I'd spend more, give out some Lash Whips, Venom Cannon, more bodies, but still, point for point, I feel like the comparison is more favorable for the Warriors. As I was saying earlier, the S5AP5 shooting isn't what they're all about, it's just the guaranteed action that makes them more appealing.

(Sorry if I mistook any points or stats, I'm doing this from memory).

Acid Spray (12" S6 Ap4 Template) and Cluster Spines (18" S5 AP5 Large Blast) might be a better choice than the rupture cannon. They are also less affected by the TFex' low BS.

Branderic wrote:Acid Spray (12" S6 Ap4 Template) and Cluster Spines (18" S5 AP5 Large Blast) might be a better choice than the rupture cannon. They are also less affected by the TFex' low BS.

If you are not taking the Rupture cannon I think a brood of Fex's or Trygon is a better investment. With the Cannon it is a monster than can shoot at tanks as it advances across the table.

Looks like Hesperus and Fizyx covered the probabilities for the T-fex, but let me copy some stats over from a blog I did awhile back...

Tyrannofex
AV10: 30.56%
AV11: 25.85%
AV12: 20.99%
AV13: 15.97%
AV14: 10.81%

Hive Guard 1 - 2 - 3

AV10: 27.43% - 47.11% - 61.78%%
AV11: 20.99% - 37.57% - 50.67%
AV12: 14.27% - 26.50% - 36.99%
AV13: 07.26% - 14.00% - 20.24%
AV14: N/A

Zoanthrope 1 - 2 - 3 (This includes the probability to pass the psychic test at LD 10 )

AV10: 30.56% - 51.78% - 66.52%
AV11: 27.16% - 46.94% - 61.35%
AV12: 22.07% - 39.27% - 52.67%
AV13: 22.07% - 39.27% - 52.67%
AV14: 22.07% - 39.27% - 52.67%

And because I've had some of my friends say that the harpy is good anti-tank....

Harpy with twin-linked venom cannon(This one is a bit tricky. For blast templates I normally set max deviation of the blast to an inch as this will hit most any vehicle directly. Bigger vehicles of course will have a greater chance to be hit. Being twin linked makes it even a bit more complicated.)

AV10: 9.60%
AV11: 7.68%
AV12: 5.62%
AV13: 3.84%
AV14: 1.92%

Enjoy.

This makes me sad.
I have a roughly 1,500 pt nid army and I havn't bought the new codex yet.
I was really thinking they might fix the fact that Nids have no long range tank killling abylities

I saw a request for deathspitters as well:

One single shot vs AV 10 BS 3: (1/2)(1/6)(1/3) = 1/36

The three shots together: 1-(35/36)^3 = 8.10%

and X amount of deathspitters: 1-(35/36)^(3X)

So for example 5 deathspitters would be 1-(35/36)^15 = 34.46%