While there are many other ways to build a deathstar battle group these days, especially among Imperial Armies that are Battle Brothers with one another, I think a very potent combination is something like this:
-Lord Kaldor Draigo
-Wulfen Pack (9 TH/SS, Pack Leader with Frost Claws and Stormfrag Auto Launcher)
-Ulrik the Slayer
The key to this force, of course, is guaranteed Gates of Infinity from Draigo, guaranteed Sanctuary from Stern, and Hammerhand on both of them. For Mobility, use Gates of Infinity to “bounce” the unit anywhere on the board starting turn 1 to set up a solid turn 2 charge.
Then, use Sanctuary to increase Draigo and the Wulfen Storm Shields up to a 2++ save (and Stern and Ulrik up to a 3++ save). Between this, FNP on all the Wulfen, and lots of T4 wounds across the entire unit, plus good use of Look Out Sir, you should be able to absorb a ton of enemy firepower between turn 1 and turn 2 (even Tau/Eldar levels of shooting) and be in solid shape to charge in wreak general havoc on your turn 2. Just to illustrate the point, in order to kill a single Wulfen with Sanctuary cast, it would take:
-54 x BS4 Bolter shots or BS3 Pulse Rifle shots
-36 x BS4 Grav Cannon/Amp shots
-32 x BS4 Plasma Gun shots
-28 x BS3 High-Yield Missile Pod shots
-11 x BS4 Lascannon or Krak Missile or Bright/Dark Lance shots
And that is just ONE Wulfen in the squad… short of your opponent having a power like Null Zone to drop their Invul save from a 2++ down to a 4++, it will be VERY hard to defeat this battle group with shooting, even highly concentrated shooting.
Once the unit does get into combat, it hits like a Mack Truck. With Hammerhand cast successfully, that is 5 x S9 AP2 I5 attacks (Draigo), 4 x S6 AP3 I5 attacks (Stern), 5 x S8 AP4 I5 attacks (Ulrik), 45 x S10 AP2 I1 attacks (TH/SS Wulfen), and 7 x S8 AP2 I5 Shred attacks (Wulfen Pack Leader) on the charge. Throw in Preferred Enemy for EVERYONE, thanks to Ulrik, and Monster Hunter (also from Ulrik, if he is your Warlord) and you should be able to “buzz saw” through multiple enemy units a turn, including even GMCs, Super-Heavies, and enemy death stars (this is still very a very deadly unit even if you have a Disordered Charge with less attacks, due to multi-charging). Successfully casting Sanctuary before you charge means that you whole squad (except the Wulfen Pack Leader) has a 3++ or 2++ save in combat, which again synergizes with the FNP(5+) on the Wulfen and FNP(6+) on everyone else (thanks to Ulrik’s Healing Balms) to let the unit absorb a ton of opposing “counter-punches,” if anything does survive long enough to hit back.
If you are not comfortable relying on Gates of Infinity, then you can use the Escape Hatch trick from a friendly building to “sling shot” the unit across the board turn 1. Alternately, you can go all in with the Deathstar concept and load the battle group in a friendly Spartan Assault Tank (with Ceramite Armor, of course) and dash it 18″ across the battle-field turn 1 to set up a turn 2 charge.
Of course, like most Deathstars, this is very pricey points-wise, so you really have to build your entire army around this unit, but even in spite of this I think this battle group can be quite competitive if you want to field a deadly, durable force focused almost exclusively on assault 😉