Iron Hands Fist of Medusa Strike Force (1850 pts)
Battle Demi Company (1310 pts)
Captain [Artificer Armour/Lightning Claw/Power Fist/Space Marine Bike/The Gorgan's Chain]
Command Squad [Space Marine Bikes, Apothecary, 3 Vets with Grav-Gun/Lightning Claw/Stormshield, 1 Vet with Grav-Gun/Power Fist/Storm Shield]
Devastator Squad [Drop Pod/x4 Grav-cannons and Grav-amps/Sergeant/Armorium Cherub]
Land Speeder [Multi-Melta x2]
x3 Tactical Squad [4x Space Marines/Sergeant/Flamer/Razorback with Dozer Blade and Twin-linked Assault Cannon]
Strike Force Command (220 pts)
Captain [Artificer Armour/Power Fist/Space Marine Bike/Storm Shield/The Shield Eternal]
Raptor Wing (320 pts)
Land Speeder [Multi-Melta x2]
Stormtalon Gunship [Twin-linked Assault Cannon/Twin-linked Lascannon]
Stormtalon Gunship [Twin-linked Assault Cannon/Twin-linked Lascannon]
The heart of this army is the pair of Captains, A.K.A. The Super Smash Bros! First a quick break down of each "brother":
"Mario" (Warlord) has a 2+/3++/2+ FnP save profile with T5, 3 wounds, IWND, and EW. On the charge, he gets either 5 attacks with a Power Fist (Str 8 AP2 @ I1) or a Lightning Claw (Str 4 AP3 Shred @ I5). On the chance that I roll a 3 on the Iron Hands Warlord Traits, his FnP becomes a 1+. So 1 in every 6 games, the only weapons that are even able to wound him are ones that don't allow FnP rolls (Strength 10, Strength D, or Instant Death).
"Luigi" has a 2+/3++/3+ FnP save profile with T5, 3 wounds, IWND, EW, and AW. On the charge, he gets 4 attacks with a Power Fist (Str 8 AP2 @ I1).
"Mario" and "Luigi" will be accompanied by a Command Squad. With their war gear, the Vets the Command Squad have a 3+/3++/3+ FnP save profile. Together with the Captains, this unit will seek out high profile enemy units (high toughness, low armor saves, etc) in attempts to fully utilize the mobile Grav. Assuming their target has 3+ armor save, each squad will be dishing out ~5 AP2 wounds per shooting phase (~7 AP2 wounds if the target has a 2+ save). If their target is instead a vehicle, they could (statistically) remove at least one hull point and immobilize it (provided that it's not a Super Heavy). If this unit comes up against a weaker "blob" unit, all of the bikes can elect to use their twin-linked boltguns instead of the Grav-guns.
To give you an idea of how tough these squads are...to wound "Mario" once, it statistically requires 36 wounds from a Battle Cannon (or weaker weapon). At BS4, that means it would have to be shot ~65 times. Using a Lascannon equivalent weapon requires 18 wounds or ~32 shots at BS4. The only weapons that will reliably wound these units are Str 10 AP2 (or better). Even when a wound gets through, each Captain has It Will Not Die and will be regenerating a wound once every third turn (statistically).
The rest of the Battle Demi-Company will prioritize getting to, and jealously guarding with ObSec, objectives. Looking at you Tac Squads! The Devastator Squad will come in on Turn 1 with their Drop Pod, hopefully landing on a centralized objective, and utilize their Grav-cannons to target units with good armor saves and/or vehicles. The Land Speeder will be used as a mobile tank hunter and/or be a downfield objective grabber (line breaker).
The Raptor Wing will be used as mobile firing support. The Land Speeder in this formation will likely play it safe on Turn 1 so that the two Stormtalon Gunships can take advantage of the formation's special rules when they come in automatically on Turn 2. After Turn 2, the Land Speeder can hopefully be utilized as a second mobile tank hunter. The Stormtalon Gunships will provide fire support where needed and if they're within 12" of either Captain, then they'll get Power of the Machine Spirit so that they can Split Fire one weapon. Thereby hopefully firing the Assault Cannons at infantry and the Lascannons at vehicles/MCs.
While this army has a formidable "Deathstar unit", it also has 9 ObSec units, including the "Deathstar", if you count the dedicated tranports, which all have It Will Not Die, separately. As a small, added bonus, this list also gets to use the Tactical Doctrine once per game to, hopefully, give one turn a particularly effective shooting/assault phase. Therefore, playing the objective game can also be done successfully.
EDIT: Adjusted as per the new SM FAQ drafts. Assuming most changes will become official.