Continuing to look at options for a Deathwatch army, another Forgeworld selection available to them is the Heavy Support slot option, the Land Raider Achilles:
-Like most Land Raiders, it has AV14/14/14 and 4HPs, plus POTMS built in. In terms of firepower, it comes with 2 x TLed Multimeltas (so good overall weapons at medium-short range) and a Thunderfire Cannon in place of the normal TLed Heavy Bolter (obviously, a significant upgrade which provides critical “artillery” type support to the Deathwatch, which generally lacks this kind of long-range shooting). On the disadvantage side, it can only hold 6 models and lacks the Assault Vehicle rule, significantly limiting its role as a traditional close combat delivery transport.
All that said, what really put the Achilles in a class of its own its special rule called “Ferromantic Invulnerability,” which makes it Immune to the special rules conferred to Melta and Lance weapons and which reduces any rolls on the Vehicle Penetration chart by a factor of -1 (so, basically, the only way you can get an Explodes! result on an Achilles is with an AP1 weapon that is either S9/10 or a weapon that has the Armourbane or Rending rules). Of course, Destroyer weapons are a significant threat, especially if you can get multiple shots of them per turn and/or if you get the luck 6+ result on the Destroyer table. Outside of that, and perhaps massed Haywire attacks, there is very little in the game that can efficiently bring down a Land Raider Achilles. Finally, the Achilles can upgrade with a Siege Shield like the one available to Vindicators (no other Land Raider variant can do this), which makes it immune to Dangerous Terrain checks (so, basically, an auto-take option).
So, given that it is not an Assault Vehicle and only holds up to 6 passengers, how can the Deathwatch make best use of this mighty War Engine? Fortunately, the Deathwatch are one of the best armies in the game at packing in tons of combat power into a small unit and making very dangerous “pound-for-pound” shooting and assault units that can actually fit inside an Achilles and take advantage of its amazing durability and superior firepower. Here are some examples I can think of:
 Aquila Kill Team with 4 Frag Cannons, Black Shield (with LC/PF), and PML(2) Librarian and Technomancy – While expensive, this small Kill Team can ride around in the Achilles with the Librarian potentially buffing it with Ignore Shaken and Stunned/BS5 (Blessing of the Machine), AV15/15/15 armor (Warpmetal Armor), and/or IWND and restored HPs (Reforge), depending on what powers he rolls up. Once they are delivered to their target safely, the Kill Team can jump out, unleash 8 x S6 AP- Rending Templates (with re-rolls of 1s, thanks to Aquila Doctrine) to obliterate almost any non-vehicle/non-MC unit (if the squad does get into CC in later turns, they first get to Overwatch with 8D3 Frag Cannon “Wall of Fire” hits and then the Black Shield can lay down some heat with up to 5 LC or PF attacks at WS5).
 Aquila Kill Team with 10 Hand Flamers (two per Veteran) and Librarian with PML(2) and Divination – The goal here is to roll up Misfortune on the Librarian… if you are able to do that, then move the LR Achilles up 18” turn 1 (12” move + 6” Flat Out), shrug off any enemy shooting (except maybe D weapons), and then move/disembark Turn 2, cast Misfortune on the target, and then hit it with 10 Hand Flamer templates. Even though the Hand Flamers are only S3 AP6, the shear amount of wounds generated should hurt almost any unit, even without Misfortune cast, but if Misfortune is “on,” then you should be able to kill even things like TEQs, Centurions, Crisis Suits, Lychguard, etc by the pure weight of AP2 Rending hits generated (and, of course, T3 hordes would just evaporate to this shooting any ways).
 Three DW Terminators, all with Heavy Flamers and Melta PFs – A bit cheaper, but still dangerous and versatile, battle group here, these three Terminators could use the Achilles to get up close with their designated target, then jump out and hit it with either 3 Heavy Flamer templates or 3 Meltagun shots (with re-rolls of 1s to Hit, using the appropriate Mission Tactics). After they have shot, they can use their 2+/5++ saves to absorb enemy counter-attacks and then either jump back in the Achilles to “rinse and repeat” or foot slog forward and charge into assault with weaker enemy units to put their PFs to good use.
 Six DW Veterans, all with double Inferno Pistols – Another version of the “Gunslinger” build mentioned in option 2, this squad use the Achilles to safely get it in VERY close (either 6” from a non-vehicle target or within 3” for a vehicle that it is seeking to bring down, then unleashes 12 x S8 AP1 Melta shots, which ought to be enough to kill almost any Super-Heavy vehicle and even many MCs, especially with re-rolls of 1s to Hit due to appropriate Mission Tactics. Another expensive build here, but potentially a very deadly one for taking out a lynchpin enemy unit in sort of an “assassin” type unit delivered by the LR Achilles.
 Five DW Vanguard, two with TH/SS and three with PF/LC, plus DW Librarian riding inside the LR Achilles – The Vanguard use the Achilles as a mobile, AV14/14/14 “shield” to block LOS from enemy shooting as they move up field (i.e. basically hiding behind it as they move) and, once they get within charge range, the Librarian disembarks and casts Prescience on them before they charge, making their attacks much more effective/efficient. Of course, as with all the other builds, the LR Achilles can also lend its shooting to support this Battle Group, with the TFC taking on hordes/light vehicles and the MMs helping against vehicles/MCs/TEQs.
Finally, aside from the battle groups described above, I think there are several allies that can help maximize a LR Achilles’ abilities in a Deathwatch army:
[a] Grand Master Azrael – Not only can be buff the squad he is riding with via his flexible WL trait, armor, and close combat stats, but he can even give the Achilles a 4++ when riding in it, making basically twice as survivable (and even difficult for Destroyer weapons to bring down quickly). Of course, he would have to start the game outside the Achilles, but could quickly hop in Turn 1 and join the DW squad for the rest of the game.
[b] Iron Hands Techmarine with Servo-Harness – He can use his 2+ save to “tank” for the squad, plus his Servo Arms and shooting weapons to increase its combat power, but more than anything he can repair damage and HPs on the Achilles on a 3+, keeping it alive even longer if your opponent is able to “attrite: any HPs.
[c] Inquisitor Hector Rex – One of the Forgeworld HQ options from Codex: Inquisition, he comes stock with a 2+/3++ save, plus solid close combat abilities (especially against Daemons). Better yet, he is PML(2) and has automatic access to both Sanctuary and Hammerhand. This means you can jump him into a LR Achilles Turn 1 to join a 5 man DW veteran squad equipped with, say, 4 Frag Cannons and 5 Storm Shields and then, once they disembark to shoot with their Frag Cannons, he can cast Sanctuary to bring everyone’s save up to a 2++, making even this small squad much more survivable. He can also cast Hammerhand to make the entire unit better at close combat, in a pinch.
There are probably many other options/tactics for integrating a Land Raider Achilles into a Deathwatch army, but these are just a few I have come up with to try and maximize their effectiveness within this faction.