So, I think the Corvus Blackstar is a unique enough addition, not just to the Deathwatch, but to the Forces of the Imperium writ large, that it rates its own dedicated review/analysis. Below are my thoughts on this new Flyer and how it fits into the Deathwatch faction from a tactical perspective (NOTE: For this review, I am assuming that Death from the Skies rules ARE in effect, since I anticipate that they will become part of the “core” rulebook next edition and so am trying to keep this article relevant in the future) —
-Corvus Blackstar (Flyer, Hover, Transport) – BS4 AV12/12/11 HP3 – Attack Flyer (Pursuit 3/Agility 2)
SPECIAL RULES: Assault Vehicle, Transport 12 (can carry Jump Infantry and Bikes)
WARGEAR: TLed Assault Cannon, 4 x Stormstrike Missiles, Armoured Ceramite, Blackstar Cluster Launcher (Bomb that can be used ever turn, not the normal Once Use Only, and can choose each time to be either S4 AP6 Large Blast [or] S5 AP4 Ignore Cover, Small Blast).
1 — Can replace TLed Assault Cannon with TLed Lascannon for Free
2 — Can replace all Stormstrike Missiles with TLed Blackstar Rocket Launcher (which shoots either 30″ S6 AP4 Heavy D6, Skyfire [or] 30″ S4 AP5 Heavy 1, Large Blast, Ignore Cover) for 3 MBs
3 — Can take either an Infernum Halo-Launcher (re-roll Jink saves) for 1 MB [or] an Auspex Array (gives Blackstar Strafing Run) for 2 MBs
4 — Can take any (or all) of the upgrade options from the following list: Searchlight, Extra Armor, Locator Beacon, single Hurricane Bolter)
Looking at the profile above, the Blackstar appears in many ways to be similar to the Stormraven Gunship, being a heavily armored Transport Flyer with significant fire support options, and a pretty hefty points cost, to match. One thing to note right off the bat is that the Blackstar can be taken as DT for a DW Veterans squad, meaning you field lots of them if you choose (and have enough points to do so). Additionally, if your are using a CAD or Allied Detachment, that grants the Blackstar “Objective Secured” which, combined with its ability to go into Hover mode, makes it into an exceptionally mobile, tough (AV12/12/11, 3HP, Armoured Ceramite, and the ability to Jink) “Objective grabber” mid-late game (remember, Fast Skimmers can move 12″, then Flat Out another 18″, for a net movement of 30″ in a single turn).
So, based on all this, I can see THREE primary roles for the Corvus Blackstar, based on how it is kitted out and deployed:
 MOBLE HORDE KILLER (TLed Assault Cannon, TLed Blackstar Rocket Launcher, Blackstar Cluster Launcher, Hurricane Bolter, Auspex Array) — In this configuration, the Blackstar can Zoom over an enemy unit and Bomb it with either a S4 AP6 Large Blast//or//S5 AP4 Ignore Cover, Small Blast in the Movement Phase, then engage a different unit at 24″ with TLed BS5 (so 97% accuracy) shooting that includes 4 x S6 AP4 Rending shots, 3 x S4 AP5 shots, and a S4 AP5 Ignore Cover Large Blast. Against anything with 5+ Armor/Invul saves or worse, like Guardsmen, Inquisitorial Henchmen, Chaos Cultists, Chaos Daemon Infantry, Eldar Guardians/Rangers, Dark Eldar Infantry, Harlequins, Orks mobs of all kinds, Gaunt/Termagaunt/Genestealer/Ripper hordes, Tau Pathfinder Teams, or Necron Scarab squads this can be devastating.
Put another way, the Blackstar in this configuration is a more powerful, more durable, more mobile version (but way more expensive) version of the Space Marine Whirlwind or Astra Militarum Wyvern, providing the Deathwatch with a long-ranged counter to being overwhelmed by cheap enemy hordes. If you can afford the points, taking two Blackstars with this configuration can be especially potent, since you can double-team your opponent with them and damage/destroy up to four separate enemy units each turn, which helps to quickly “clear the Drop Zone” for you follow-on Deathwatch “scalpel” Kill Teams. One more thing, in a pinch, the Blackstar Rocket launcher provides some Air-Defense capacity for Deathwatch that they generally lack, especially since they don’t have access to the AA tanks of the Space Marine Codex.
 HEAVY FIRE SUPPORT TRANSPORT (TLed Lascannon, 4 x Stormstrike Missiles, Blackstar Cluster Launcher, Extra Armor, Auspex Array) — In this variant, the Blackstar could start the game in Hover mode on a Skyshield Landing Pad (giving it a 4++ save without Jinking) and engage a key enemy vehicle or Monstrous Creature with a BS5 TLed Lascannon and 4 x BS5 Stormstrike Missiles in an “alpha strike” role to either kill or mortally damage that designated enemy unit at long range. Turn 2, the Blackstar could switch into Zoom mode, continue to engage with its TLed Lascannon and Cluster Launcher Bomb, and carry a DW squad toward a designated target where, on Turn 3 it could drop back into Hover mode and disembark the squad to shoot and charge an enemy unit, as required.
This is kind of the “versatile” variant of the Blackstar and helps a Deathwatch army by providing long-range, high strength/low AP firepower that most of its units lack and still providing critical mobility options for the DW Veterans, Terminators, Bikers, Vanguards, and/or Kill Teams that they need to be effective in competitive games. Ideally, you would field this variant in pairs as well, but that would require two Skyshields, which means two CADs, which makes things much more complicated when list-building. You could start them in reserve and then, if both Blackstars came in turn 2 together, “beta strike” your opponent with 2 x TLed Lascannons and 8 x S8 AP2 Stormstrike Missiles, provided they came on in Hover mode and did not move more than 6″ (Fast Vehicles can shoot ALL their weapons if they move 6″ or less). This might be the Deathwatch’s best “organic” long-range option for dealing with Wraithknights, as BS5 means you will likely get 9-10 hits and S8/9 AP2 gives you solid chances of actually inflicting Unsaved Wounds on those T8 monstrosities.
 HEAVY ASSAULT TRANSPORT (TLed Assault Cannon, 4 x Stormstrike Missiles, Blackstar Cluster Launcher, Extra Armor, Locator Beacon Infernum Halo-Launcher) — Basically the “stock” Blackstar configuration, except with the additions of Extra Armor, Locator Beacon, and the Halo-Launcher, the goal of this build is to get your dedicated Assault unit into close combat at all costs, be it a TH/SS Terminator squad, Vanguard Vets with lots of PWs, or a Veteran Squad rocking SSs and Heavy Thunder Hammers. You can start in reserve, hopefully come in Zooming on turn 2, use your re-rollable Jink and “Hard to Hit” status to survive enemy shooting, and launch an assault on Turn 3, or you can try the Skyshield trick of starting on the board in Hover Mode, move 12″ + 18″ Flat Out Turn 1, rely on your AV12 and re-rollable Jinks to weather the storm of enemy shooting, and then Turn 2 launch an assault with your embarked squad. The Locator Beacon provides added flexibility to bring in other DSing (or Gates of Infinity) units precisely as the Blackstar dashes up-field and, once the assault unit has disembarked, allows the Blackstar to continue “pulling” in reserves accurately as it moves/shoots/seizes Objectives independently.
Using the Skyshield method (described above), you could even load up a heavy-hitting Allied assault unit (e.g. Space Marine Assault Centurions or DA Deathwing Knights or DA Black Knights or SW Wulfen or Sororitas Repentia with attached Priests or Inquisitorial Death Cult Assassins with attached Priests or GK Purifiers or Skitarii Infiltrators with Taser Goads or Death Company with attached Astorath) and then hopefully deliver them into combat no later than Turn 2 (the allied unit would start the game on the Skyshield next to the Hover-mode Blackstar, then load into it turn 1 before it moves 12″ + Flat Outs 18″). The key advantage the Blackstar has here over, say, Stormwolves or Stormravens, is the re-rollable Jink save, which increases its save from 50% to 75%, making it much more likely to successfully gets its embarked squad into combat (Note: If one of your Psykers can successfully cast The Shrouding within 6″ of the Blackstar, then it becomes a re-rollable 2+ Jink save, making it all but invincible against anything without Ignore Cover shooting).
As per above, I think the Corvus Blackstar is quite a solid component of any Deathwatch army and provides many key functions that otherwise would be left lacking in a “pure” Deathwatch force. Of course, they are expensive points-wise, so you have to really have a plan to integrate them effectively into your army and battle-plan, if you plan to bring one or more Blackstars in your army list