As I continue to look out how Deathwatch can be played in a competitive manner on the tabletop, another group of allies that I think work quite well to support them is the Skitarii faction. Here is how I see an allied force of Skitarii units (either from formations or in the Skitarii Maniple detachment) integrating with a primary detachment Deathwatch army:
 Skitarii Vanguard – Costing less than 2 MBs per model and coming stock with a 4+ save, FNP(6+), Relentless, and a 3 shot Radium Carbine, Vanguard are exceptionally good value infantry who can provide the “economy” complement to the expensive Deathwatch forces. While they are somewhat fragile, with their T3 and lack of any organic Transport options, Vanguard can put out plenty of solid firepower for their points, with the Radium Carbine generating lots of wounds, even on T8 Wraithknights, due to its high rate of fire and Rad Poisoning rule (each To Wound roll of a 6+ causes two automatic wounds, regardless of enemy toughness). Radium Carbines obviously combine brilliantly with the Misfortune power, if any of your DW Librarians roll that up on the Divination discipline. On top of this, they can take 2 Special Weapons (bumped up to 3 if they take a full squad of 10 Vanguard) and have access to 3 shot Plasma Calivers, long range Transuranic Arquebuses, and rapid firing Arc Rifles.
Of these, I think Arc Rifles have the most value for Vanguard allied to a Deathwatch army, since it provides solid S6 AP5 shooting against non-vehicle units and exceptional (and rare) Haywire shooting against vehicles. A couple of Vanguard squads using the “Protector Imperatives” from their Doctrina Imperatives rule along with max Arc Rifles (and an Arc Pistol on the Vanguard Alpha) can efficiently deal with enemy vehicles, even massed transports like in a SM Gladius detachment, leaving the Deathwatch units free to use their potent (but limited) firepower on more important targets like elite infantry, MCs, and HQs. Finally, Skitarii Vanguard have the special “Rad-saturation” rule, which causes any enemy units locked in close combat with them to have -1T. This combined beautifully with Deathwatch close combat units, since it reduces T6 enemies, like Riptides and Hive Tyrants, to T5 (making them vulnerable to ID from Heavy Thunder Hammers), T5 enemies, like Thunderwolf Cavalry, Necron Wraiths, and SM Centurions, to T4 (making them vulnerable to ID from THs/PFs), and T3 enemies, like almost all Tau/Eldar/DE/Astra Militarum/SoB infantry, to T2 (making them vulnerable to ID from Power Swords, Guardian Spears, Xenophase Blades, and the “Thief of Secrets” Relic).
Finally, when part of the “Skitarii Maniple” detachment, Vanguard gain both Scout (except the Outflank portion of that rule) and Crusader, making them surprisingly mobile and thus able to synergize well with DW units on Bikes, in Drop Pods, or riding in a Transport vehicle like a Rhino or Corvus Blackstar. Additionally, even though they cannot start the game inside a Deathwatch vehicle, Skitarii Vanguard can jump into an allied Deathwatch transport turn 1 and use it to enhance their durability and mobility (i.e. a squad of 5 Vanguard with two Arc Rifles combines beautifully with a DW Rhino, since it protects them from small arms fire, moves them up the board quickly, and has two firing points for their Haywire shooting to fire from).
 Sicarian Infilitrators – A somewhat unique and unusual unit, Infilitrators cost about the same as Terminators, but are significantly more fragile, with T3 and a 4+/6++ save. This is somewhat offset by their 2W, FNP, and Stealth USR, but in general they are quite fragile for their points. Where Infiltrators really gain their value, and where they become an invaluable ally to a Deathwatch army, is in their mobility, damage potential, and “debuffing” capability on the enemy.
With the innate ability to Infiltrate (plus Scout and Crusader if part of a Skitarii Maniple detachment), plus the amazing Dunestrider rule (+3” to their Movement, Run moves, and Charge ranges!), the Sicarian Infiltrators can easily get where you want them to be by turn 1 (or turn 2 at the latest) without depending on transports or deep striking (they also have a very robust charge range, thanks to extra 3” from Dunestrider). This combines well with Deathwatch forces by allowing Sicarian Infilitrators to be in position near enemy lines starting turn 1, when DW Veteran squads and Kill Teams will likely be arriving by Drop Pod. This mobility (i.e. 9” move + 3+D6” run = 14-18” displacement each turn, if they do not shoot or charge) also makes the Infiltrators solid units for claiming objectives, moving up enemy flanks, and/or escaping enemy forces when required. Overall, the Sicarian Infilitrators’ high mobility is an excellent complement to Deathwatch forces and, in a pinch, you can always load the Infilitrators into a friendly DW Land Raider or Blackstar after turn 1 for even more mobility.
In terms of damage potential, in many ways Infilitrators “mirror” Deathwatch units, with high damage potential residing in a relatively fragile unit. If equipped with Taser Goads and Flechette Blasters, Infiltrators can put out 5 x S2 AP- Shred shots at 12” (per model) followed by 4 x S6 AP- Taser attacks on the charge (again, per model), which makes them exceptionally at dealing with large hordes that would otherwise potentially “swarm” a Deathwatch army down (Note: Like with Radium Carbines, the Taser Goad/Flechette Blaster loadout combines marvelously with the Misfortune power, since you generate so many chances at getting Rending attacks). Finally, Infilitrators have the “Neurostatic Aura” special rule. More than anything else, this is probably the reason you would take them to ally to a Deathwatch army. Basically, it any enemy models within 6” of a Sicarian Infiltrator suffers -1 to its WS, BS, I, and Ld. In conjunction with the Infilitrators ability to Infiltrate and Scout, this means you get them right into the enemy’s DZ turn 1 and “debuff” selected units, which synergizes amazingly with a Deathwatch Drop Pod spearhead (and the ability to “teleport” in more DW units with the Beacon Angelus). In particular, the ability to reduce enemy BS by -1 means that, after the DW Drop Pods have arrived and unloaded the firepower of their squads, in the next turn your opponent will be shooting at (and charging) those units at significantly reduced capacity, which in turns enhances the survivability of your costly Ordos Xenos Marines.
 Ironstrider Ballistarii – As mentioned in previous articles, one of the weaknesses of the Deathwatch army overall is strong medium-long ranged shooting. The Ironstrider Ballistarii is an excellent ally to help compensate for this, with the options of either a TLed Cognis Autocannon (11 MB per model) or a TLed Cognis Lascannon (15 MBs per model) and the ability to take between 1 and 6 Ironstriders per squadron. Besides being able to be hyper accurate using Doctrina Imperatives (i.e. re-rollable 2+s to Hit on up to three turns a game), the Ironstriders can also provide significant shooting during Overwatch, against Flyers, and against units that have Invisibility cast on them (i.e. with TLed and Cognis rules, the Ironstriders hit all these targets with 50% accuracy, vice the normal 16% accuracy for “regular” Snapshots). Combine all this with the superior mobility of Scout, Crusader, and the Dunestrider rule (mentioned above) and you have an affordable, potent “skirmisher” unit that can supplement many of the weakness (especially in terms of long range firepower) of a Deathwatch army.
 Onager Dunecrawlers – Finally, whereas Ironstriders provide significant firepower support, albeit on a fragile platform, to a Deathwatch detachment, Dunecrawlers provide more expensive but much more durable shooting capacity as allies to the black and silver Astartes of the Ordos Xenos. With AV 12/12/11 and the ability to have a 6++, 5++, or 4++ save (based on how many of them are in each squadron) on a walker chassis that only costs 18 MBs “base,” Onagers provide a very affordable, at least compared to Land Raiders and Blackstars, vehicle fire support supplement to a Deathwatch primary force. Additionally, Onager Dunecrawlers can be equipped with multiple weapon options to support the needs of a Deathwatch army, including an Eradication Beam (close range, flexible shooting against both vehicles and infantry), TLed Heavy Phosphor Blaster (anti-MEQ at range plus the ability to “mark” a target and reduce its cover saves against other friendly shooting), Neutron Laser (long-range S10 AP1 Concussive Small Blast for anti-vehicle/MC work), and the Icarus Array (high volume/power shooting against any enemy flyers, FMCs, and/or skimmers, which makes it great against Eldar, DE, Tau, Necrons, and Tyranids). No matter what option you go with, have one or more Onager squadrons as an ally to your Deathwatch army is a significant boost which can make the rest of your units more effective with their shooting and ability to absorb damage away from the expensive/fragile DW squads.
As you can see, there are solid uses for each of these Skitarii units in an allied force to a primary Deathwatch detachments. I did not even discuss Skitarii Rangers, Ruststalkers, or Sydonian Dragoons (and these all have the potential to enhance a Deathwatch army as well), but even if you just stick to the Skitarii forces discussed above, I think you can make solidly competitive combination with the squads vehicles, and Kill Teams of a Deathwatch main army.