I can't let booored be the only one posting decklists.

Preliminary concept:

Cato Sicarius pulls resources every time an enemy unit dies at his location. The deck objective is to capitalize on this early on and try to overwhelm the opponent.

Watching the GenCon demos, it seems like there will be a fair percentage of games where both sides have pretty large #s of troops at the same planet, making AoE a possibly viable strategy.

Key tactics: AoE and Ambush. (Ambush in an Eager Recruit, Drop Pod Assault something, and then use Maxos to ambush in a Dreadnought. CREEEEEEEDD!!)

(Blue for SM cards, Green for AM cards)

Warlord:

Cato Sicarius

Signature Squad:

Sicarius' Chosen x 4

Cato's Stronghold x 1

Fury of Sicarius x 2

Tallassarian Tempest Blade x 1

Army (24):

Eager Recruit x 3

Ultramarine Dreadnought x 2

Tactical Squad Cardinis x 3

Blood Angels Veterans x 2

Daring Assault Squad x 3

Deathwing Guard x 2

Veteran Brother Maxos x 2

Land Raider x 2

Ratling Deadeye x 3

Mordian Hellhound x 2

Attachment (4):

Godwyn Pattern Bolter x 2

Hostile Environment Gear x 2

Event (10):

Indomitable x 3

Exterminatus x 2

Drop pod assault x 2

Suppressive Fire x 3

Support (4):

Holy Sepulchre x 2

Catachan Outpost x 2

Tactical Squad, Assault Squad, and the Mordian Hellhounds give this deck a total of 8 units with AoE capability. Sicarius' Chosen lets you pull more enemies into a clump to maximize AoE output. Ratling Deadeye (possibly coupled with Catachan Outpost) can take out major threats in the Ranged phase, or soften up higher HP targets before the firestorm.

Once all the little units have been AoE'd down, Sicarius should be resource-flooded, letting you drop heavy hitters like Deathwing Guard or a Dreadnought.

Hostile Environment Gear, Land Raiders, and Indomitable can keep units alive through a fair amount of punishment, and Holy Sepulchre can hang out just in case.

Suppressive Fire can hold off the enemy's biggest threats (like something with Cybork Body), with an Exterminatus in the wings just in case.

This deck (with some possible tweaks) should be extremely potent against swarm and token decks, although it may have some problems with decks that rely on smaller numbers of tanky units.

Possible weaknesses:
*Flying - this deck doesn't have many good hard-counters to Flying. The bolter is the only real counter to bigger flyers, so if Flying starts becoming more common this deck might suffer

*Command Struggle - I am not really sure how well this deck will be able to run the command struggle. My first drafts of this deck used Iron Hands Techmarine and Promotion to get some edge in Command Struggles, but they had to be trimmed out for space.

Other possible includes:

Promotion / Iron Hands for better Command Struggle presence

Bribery - another way to force your opponent to cluster units together for an AoE firestorm or Exterminatus

Raven Guard Speeder or Assault Valkyrie - Give the deck a better set of answers for flyers

Elysian Assault Team - more ambush shenanigans

42 card seems really tight for a deck. It has to have 2 functioning engines (command struggle and battle) and have answers or counters to enemy tactics. A lot of cards that I wish I could fit.

60 Card deck limit instead of 50? I wish...