Forge World previewed the model in their latest bulletin post at the very bottom. The vorax looks a lot different than I had mentally imagined which is a good thing. I had an image of a castellax class that just had different guns/arms. That's what they did with the destructor and secutor models they put out. The models are the same with just different arms and weapons. So much to my surprise they didn't go that route. It looks like some sort of insectoid robot and should fit right in with everything else mechanicum. The aesthetic of the army is so different from everything else that in the 40k/30k universe that it stands out in a good way. I've had people come up and ask about the army every time I play somewhere because it is so unique and different looking.
Now the fluff for the vorax basically says that they were created by the mechanicum to be wandering search and destroy predators. Mars always has a ton of rouge machines and mutant vermin running around and these guys just walk around like the orkin man getting rid of the pests. They are also evidently used to help cull the population during times of famine or plague when the martian overlords decide some of the human laborers need to go.
The rules for these guys are decent, but I wouldn't call them must take good. For the cost of a basic space marine predator you get a monstrous creature that is similar in stats to a castellax. The difference is the vorax toughness is 1 lower, has 1 less wound, 1 higher initiative, and only has a 4+ save with no invulnerable. Weapon wise it has a lightning gun, 2 rotor cannons, and power blades for melee. It has night vision, fleet, and scout. The vorax also has the cybernetica cortex which has a bunch of rules that I won't get into except to say that it makes the unit fearless, but must attack the nearest enemy unit if it is within 12 inches of an enemy and has no cortex controller nearby. Again there are a couple other things the cortex does but those are the only 2 that matter for what I'm going to talk about.
As far as upgrades go, you can add up to 4 vorax to make a maniple of 5. You can give them a search light which is completely useless since they already have night vision. They can take frag grenades which might be a wise purchase. They can be given an enhanced targeting array which makes them BS5 and makes any unit that you shoot at -1 on any potential cover save. You can swap out the lightning gun for an irad-cleanser which for those that don't know is a flamer on steroids. It has the fleshbane rule, and rad-phage. Rad-phage reduces a models toughness by -1 for the rest of the game if it loses a wound to a weapon with the rad-phage rule. Not great since most models only have 1 wound to lose, but it can come in handy. The real reason to take it is because its a flamer that will always wound on a 2+ due to fleshbane. Lastly you can upgrade a single vorax, and thus can't add anymore to the unit, with the paragon of metal special rule. The paragon of metal special rule give it rampage and it will not die. It also means it ignores the attack the closest enemy within 12" rule. It does make it so the model can never count as a scoring unit and cybertheurgy (mechanicum psychic powers basically) failed attempts will pretty much always go badly for you.
Alright so I've given a general outline of the vorax rules, now what do you do with the vorax? Well the way I see the vorax being used is as a horde killer. The mechanicum list has lots of models with a high toughness and multiple wounds. They also have a lot of AP3 and AP2 guns. For the most part, when you shoot, you will kill your intended victim. What you don't have is something that can quickly kill blob squads. The vorax fills that role nicely. Rotor cannons are strength 3 AP6 salvo 3/4 guns. They will always get 4 shots since monstrous creatures have relentless. So figure each vorax has 8 shots a turn. Against any horde army the vorax will find a use, against something like marines, or necrons I don't really see a use for them at least as gun platforms. The lightning gun is a 1 shot 18" gun that is strength 7 ap5 and has shred'/rending. Its a nice gun but since the vorax can only shoot 2 weapons I don't see it being used all that much unless you're taking shots at light armor tanks or high toughness creatures, but again that would be a waste since the rotor cannons won't help you. Potentially the enhanced targeting array would be nice for the vorax as a gun platform, but its 15 points and the -1 to the cover save part of it is just wasted since your guns are AP6 or AP5. The BS5 is nice, but not a must have since you will be taking 8 shots. I just don't think its a worthy upgrade for the vorax.
If you want to use the vorax as an assault unit, I think that's the best plan for them, although the WS3 could be a potential problem. If you do decide you want to run them as an assault unit, you definitely want to scout them forward and take the irad-cleanser and frag grenade upgrade. They should perform well in this function provided you make sure that you are the one charging in. On the charge each vorax will have 3 attacks at strength 6 AP2 rending, initiative 4. The toughness 6 means that even though they only have a 4+ save most attacks won't hurt them anyway. Besides the WS3, the other thing you have to worry about is the programmed behavior. You have to make sure you position yourself correctly otherwise you might not be able to charge the unit you really want to charge. That 12" rule says you must shoot at and attempt to charge whatever unit is closest to you if a unit is within 12". So its possible you may have to shoot at a land raider and assault it instead of the tactical squad behind it. Granted if you have a cortex controller within range that's not an issue, but these guys should really be out ahead of your army trying to get into assault.
All in all I think the vorax is a cool model with rules that fit the fluff of it. I'm going to pick up a squad of 5 when they come out, but I don't see it as a must use for myself. I'm not a huge fan of assaults but that's because I tend to play my necrons a lot. Now as a 1, 2 punch with some of the Ursarax Cohorts, you could really make a nice assault army for the mechanicum. Of course the Ursarax I will go over when they get the model out for that. Hope this was interesting and educational.
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