I've had a lot of success with stark siege. for this deck, your key cards are:
whispering wood: the point is to rush to 15 powers. epic battles are mandatory.
battle for shield islands: same. plus, we do have a fleet so that's good.
northern cavalry flank: you're going to play a lot of epic battles, as well as storm of swords and mummers ford. these guys don't kneel, they are absolute beast.
king's robb host: same as ncf. sometimes you get unlucky and you can't pay for robb's host. personally I run city walls rather than at the gates, so that's never THAT much of a problem
king robb: for armies.
jeyne: to get robb
fleet from wolfs den: amazingly cost efficient. war crest is cool if you choose to have die by the sword. renown is amazing in a rush build (which siege is). they work well with shield islands
syrio: this guy can bounce in and out for each epic battle. seriously it's ridiculous. let's say you play 3 epic phases in the same round, syrio can participate in all of them because they are 3 individual phases.
distinct mastery: this is a rush build. sometimes it's crucial to stand cavalry flank, or king's robb host if they were knelt by something before they could wreck some challenges. you can also stand robb and play a second army.
and of course, the siege of winterfell
other cards I like:
die by the sword
to be a wolf (whenever it's safe to play mummer's ford as your first plot, otherwise fury of the wolf, which is my chosen restricted)
jorah and carrion for stealth.
I'm not a fan of lucas blackwood/umber beserk. sometimes they work and sometimes they don't. I'm not a fan of the newest karstark army either. not having the agenda ruins this deck completely.