GK - Combined Arms 1080 pts 21 models
I'd agree with Xabre - the Nemesis Strike Force will let you put on early pressure to support the Knight, which you really need.
Good, although I'd probably want to find the points for the Domina Liber Daemonica since your psychic powers will be all but unopposed against Necrons - may as well make the most of that fact (almost all the Sanctic powers are good at fighting Necrons - Vortex of Doom helps you crack their universal AV13; Cleansing Flame gives Warriors a hard time, Hammerhand lets you churn through their infantry, lowering their leadership that extra few points to let you run them down almost automatically; Gate of Infinity lets you fight them at their own game if they have Veils of Darkness, or generally helps with mobility which is always good; Purge Soul is never very strong, but you can snipe out Resurrection Orbs or Crypteks with it; and Sanctuary, while not as strong as it usually is against the high AP of Necron firepower, will save your bacon if he's packing some Warscythes).
Terminators
Justicar NFS; SB
3 x GK Term NFS; SB
1 x GK Term NFS; Psycannon
Swords are fine if you're strapped for points and they're probably the second best squad-wide weapon after Falchions. You'll probably want a Hammer to stop one dude with Sempiternal Weave tanking your attacks all day, but arming a squad with them is very expensive with diminishing returns; Staves are likewise a niche choice. Here I disagree with Xabre; Halberds are essentially a dud entry. Against Necrons, particularly so. Str7 just isn't appreciably more than Str6, especially when you have Force to deal with any roving Tomb Spyders or C'tan or what have you. They're super-cheap, certainly, but juts because something is cheap doesn't mean it's a good deal.
Strike Squad
Justicar NFS; SB
3 x GK NFS; SB
1 x GK Psycannon
Again, I agree with Xabre. Strikes are just inferior to the other forms of PAGK - my favourite are Purifiers, but Interceptors and arguably Purgators are simply better than Strike Squads (you're GK - you're already super-expensive, so why not pay a little bit more and be super-good as well?). Drop these guys.
Purifiers
KotF NFS; SB
Pur NFS; SB
Pur Inc
Rhino
I'm not really sure what this squad loadout is, but 10 Purifers with 4 Incinerators is a great loadout. They gain a hell of a lot (well, they're unusable without) the Nemesis Strike Force, where they can Deep Strike, Run and then shoot off their Incinerators.
Storm Raven
TLMM; TLLC; 4 x Storm Strike Missiles
Twin-Linked Assault Cannon is probably a better choice than the Lascannon due to how they interact with Jink - more shots is better, especially since Jink has minimal effect on Necron aircraft (as they have Tesla -
@falcoso can attest that snap-shooting is pretty much just as good as regular shooting with a Twin-Linked Tesla Destructor). It's only good as anti-air, however, and it's a pretty expensive way of doing that considering how cheap it's targets will be.
Lascannons will bounce off anything important that Necrons can give - AV13 with Jink or even regular cover (Necrons can easily get 4+ cover through their ability to switch Night Fight off and on). Drop it completely.
Nemesis Dreadknight
PT; HPC; 2 x PF
I prefer the Heavy Incinerator as it lets you kill units in Ghost Arks and has roughly the same anti-infantry output as the Heavy Psycannon for nearly half the price, but the Heavy Psycannon certainly has merits (it's great to shoot into the rear armour of Necron vehicles, for example - easily reachable with a PT).
We know him, we love him.
Henchmen
7 x Acolyte BG; CS
3 x Servitor MM
1 x Psyker
(not sure what tree, since will have Coteaz in this squad with Div.)
Chimera
They're not going to be able to sit still to fire those Multi-Meltas if the Necron player is any good, and Str8 vs Av13 with cover is hardly promising. Psyker is good for an extra Warp Charge - as I mentioned, Necrons can't stop you effectively at all, so maximising your Psychic Phase would go well. The Bolter Acolytes are pretty worthless; any Necrons that aren't dying to the Storm Bolters of the GK (tip; it won't be many) won't care about a few Bolters, so cut down to 2 Bolter Acolytes, 3 Meltagun Acolytes, and maybe a Psyker if you have points to spare.
Good, and better with the Nemesis Strike Force.
Henchmen
Acolyte BG; CS
Servictor MM
Valkyrie LC; Hell Strike Missiles
Again, not sure what's going on with the Servitors. Just bring Acolytes with Meltaguns. Valkyrie should stick with the Multi-Laser, but bring the Multiple Rocket Pods and if you can afford them, the Heavy Bolter Sponsons.
He's great.
It's great
if you can support it with a bunch of other early threats.
I'd be tempted to drop the Stormraven, Razorback, Rhino for the Purifiers, spare Bolter Acolytes and Strike Squad, replacing them with a second squad of Terminators and a 5-man squad of Purifiers with 2 Incinerators. You fill in the slots for the Nemesis Strike Force, so do that because Rites of Teleportation > Objective Secured. Then, with the leftover points and in this order of importance, get as many Incinerators as humanly possible on the Purifiers, swap the MM Servitors for Meltagun Acolytes, the Domina Liber Daemonica on the Librarian, and whatever else I suggested up there that you have points for.
You'll end up with a nice alpha-strike (although I just realised, no Reserve Manipulation means that bad rolls could really screw you up if a lot of stuff doesn't arrive turn 1), with the threat of the Knight backed up by 10 Terminators, 15 Purifiers (in 3 squads of 5 through Combat Squads, so you can get +6 Warp Charge and throw Cleansing Flame around all the more - Necron Warriors and Wraiths really, really hate Cleansing Flame, and it's a surprisingly effective anti-flyer tool if you're looking to plink off a Hull Point or something) with support from the Vindicare and later, the Acolytes to shore up a weak point/snipe a troublesome vehicle/grab objectives as appropriate.
