In the lore of the Grey Knights chapter of Space Marines, the Techmarine is a singular and aloof figure, trained and conditioned under the ideals and traditions of two disparate organizations - the Adeptus Mechanicus and his Battle-Brother Knights of Titan. His role within the Grey Knights Brotherhoods is crucial, holding up and keeping in good repair the chapter's limited number of transports, Storm Ravens and Land Raiders and preserving the chapters most venerated warriors in their mighty Dreadnoughts.
In the Codex, the Techmarine is an Elite choice in the troop organization chart, a slot that usually doesn't have a lot of internal competition because if you're running a bunch of Purifiers you're probably taking Castellan Crowe. Same goes with Paladin lists: they will more likely than not include Kaldor Draigo. At ninety points each with no upgrades, the Techmarine is fairly expensive for a frail one-wound unit, even in the slightly better than MEQ artificer armor. But with a wargear options list as long as my arm, the Techmarine can come in a couple different flavors to fill some unique roles in a Grey Knights list and a group of special rules that range from the situational to the all-around awesome (a second Hammerhand? yes, please).
Close-Combat
The Grey Knights Techmarine is really a close-combat oriented animal. He can be kitted out as a long-range heavy weapons platform or as a baby-sitter to a line of Psyflemen but will be reliant on favorable situations and some lucky rolling to earn his points. A naked Techmarine has a power weapon and a standard space marine statline but don't let that discourage you yet. Equipped with a full servo-harness, he has an additional two S8 power fist-like attacks that can ID most characters and puncture holes in all but Land Raider armor.
Now's you can let the space marine statline discourage you. Because at 90 points base he's the near equivalent to an entire five-man Strike Squad going down to a single failed save at T4. He is in artificer better with a slightly better than MEQ save and he can be upgraded with a couple different close combat options to increase his effectiveness, for a price. However, a Nemesis Force Sword is a waste, gaining a force weapon and Daemonbane for five points. There's a Force Halberd but it's not worth the cost at one base attack. Neither are the Falchions. A Nemesis Force Hammer is plausible but doesn't make much sense considering he comes with 2 S8 attacks base. Which leads us to the Nemesis Warding Stave, which for a close combat Techmarine is an absolute must. This notches the Techmarine up to 115 points base, but in CC with a 2+/2++ save he'll have the best save possible barring re-roll shenanigans.
But that's assuming your opponent has reason to pick him out in CC. Two BS4 "power fist" swings with a really sick save are still not worth the investment. The Techmarine's special rules sweeten the deal a bit. He's a Psyker (Level 1) with star GK psychic ability Hammerhand, which means any unit he's in will get their own cast with Brotherhood of Psykers on top of the Techmarine's second Hammerhand, resulting in a unit that will be wounding MEQs on 2s.
It's in the extra wargear choices that the Techmarine's true effectiveness and CC utility are revealed. Unique to any entry aside from HQ, the Techmarine can take any of the Grey Knights fearsome grenade loadout. Blind grenades are neat but with the frequency of I6 in the GK CC units and the chance of irrelevancy by the much better Psychotroke grenades they're only a good place to spend points that are left over. Meltabombs: don't bother. Rad grenades make every single attack in your unit hit harder - by reducing the enemies toughness by 1, a reduction which does affect whether they get IDed by a hit. And for ten points, if you're making a Techmarine grenade courier they're a must, as our these: the crown jewel of a CC Techmarine's wargear, the Psychotroke grenades.
Psychotroke grenades just like Rad count as being used whenever your unit gets into close combat whether they assaulted the enemy or vice versa. While you've got a 1/6 chance of not doing nothing and a couple effects that are almost duds against some of the more fast-and-stabby CC specialists, the psychological effect these will have on your opponent not to mentioned the real effects of giving your unit re-rolls, or reducing the enemy to 1 attack or even 1 initiative is brutal. In a bigger game, I'd even taken Psychotrokes with the overlooked Empyrean Brain Mines. The biggest set-back with these is getting the Techmarine in base-to-base contact with the model you want to neutralize. This'll be a bit easier with CC independent characters, as they want to be in smashing range of everybody. But as they're tricky to use, I'd say leave them at all for all but the biggest battles in which you have a definite plan of getting your Techmarine unit into close combat with the enemy's hardest hitters and often.
Lastly, don't forget the Techmarine carries all the standard GK space marine grenades and putting one in with Death Cult Assassins (or other Henchmen) gives them the bonus of Frag and Krak grenades as well.
Shooting
Techmarine's have just a few wargear options for shooting. My Techmarine's always carry a storm bolter, but I'll be the first to admit that's entirely for fluffy, modeling reasons. Otherwise, meh, why even spend that many points of assault 2 over rapid fire. My first Techmarine incarnation, however, was a Conversion Beamer marine. Just a body to sit back in a bunker and blast away at the enemy. Against a heavy mech list, that just sits back on its own far side of the map and tries to blast you into nothingness blast shots of doom, the Conversion Beamer is not such a bad thing. You'll be getting either S8 or S10 shots out of it and though it's difficult to do the math on a scattering template, experience tells me you'll be hitting something damn near most of the time. Here's the thing, though.
A Conversion Beamer-ed techmarine lands in at 110 points. Granted, you'll get to Bolster the ruins you stuff him in, but you can get a Xenos Inquisitor with the same weapon, an inch more of potential scatter for about 40 pts less. And honestly, when you're looking to cash in on a cheap but useful HQ, the Xenos Conversion Inquis. is a damned fine idea. It's even more expensive to load out your Adeptus Mechanicus Grey Knight with an Orbital Strike Relay...
As it turns out, a single, variably heavy, variably accurate shot is not worth the price tag of 100+ pts if you're just tossing it in as a tag-along extra. These kind of shooty-based Techmarines aren't competitive in standard lists. There are some oddball lists that want to mass OSRs and Conversion Beamers and in that case, you'll probably be chewing up all of your Elite slots with pricey shooty Techmarines but in that particular situation it makes perfect sense to your list. The one exception I can think of, regularly speaking, is if you want a TM to sit back and babysit your Psyflemen, keep them weapons ready and mobile and still give it something to shoot with in the downtime.
For this gunline Techmarine babysitter, I went with the Conversion Beamer over the Orbital Strike Relay because a single OSR, scattering at all times at the full 2D6, just isn't going to be accurate enough to do a heap of good. Sure, the Techmarine gets to keep his Servo-harness if he doesn't opt for the Beamer, but with the psychic skill Reconstruction you're still fixing a Weapon Destroyed or Immobilized result with a little over 50% consistency. The Beamer also is 30 pts cheaper and at the range that the Psyflemen will probably be sitting at could very plausibly get the full strength 10 hit that can puncture any armor. Obviously, going the OSR route will get you better repair results but I think that balancing price with the shooting potential of the Techmarine's weapons load-out whenever they are not repairing puts the Conversion Beamer ahead of the Orbital Strike Relay, even if it feels counter intuitive.
Utility
Bolster the Defenses is a minor Techmarine special rule but an important one to work fully into your battle plan for the scenario. It's often easiest to pick a ruin on your side of the table and just plan on sticking a long-ranged heavy unit in their to dish out the pain and get an extra cover bonus for its troubles. Vindicator Assassins, some varieties of Razorback, and Psyflemen dreads are great picks for such a task. For the somewhat more aggressive player or one that doesn't have anything notable beyond the 24" GK kill range, choosing a ruin a bit further into the center of the battlefield can mean that you're racing against your opponent to get to it, but if you've done your deployment and movement phase right you should be reaching it first. A Bolstered midfield ruin can be a brutal Psycannon bunker, especially in objective-capturing missions, where 24" from board center can reach more of the board than you'd think.
Reconstruction is sort of the Techmarine flavor skill and a sweet bonus should a situation ever fall into your lap where it'd be perfect to use it. As a general rule, I'd only bother moving your Techmarine into position to repair a tank Immobilized out of range of the heat of battle or a crucial Multi-melta or Lascannon. No other weapon type is really going to be bother repairing, unless that TL Assault Cannon is your last hope for rending through that Land Raider's armor.
Don't forget he'll give And They Shall Know No Fear to any henchmen unit he may be with.
Advantages
Only non-HQ unit that can take GK grenades
Is an IC with Pskyer (Level 1) and Hammerhand
Minor special rules that when used correctly can really start to make back his rather steep point cost
Best way to spam OSRs and Conversion Beamers in a sit-back-and-orbital-strike list
Disadvantages
Actual flavorful Reconstruction skill somewhat limited in its practical application
Expensive unit when kitted out for full close combat utility
Only one T4 wound and no invulnerable save unless you give him a Warding Stave for a 2++ in CC
Flavors
Grenade Basket
Techmarine
-Nemesis Warding Stave
-Rad, Psychotroke Grenades
Heavy Support (OSR List)
Techmarine
-Orbital Strike Relay
-0-3 Servo Skulls (for Deep Striking, as they do not reduce OSR scatter)
Psyflemen Babysitter
Techmarine
-Conversion Beamer
-0-3 Servo Skulls
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Image from 3++ Is The New Black
