Well, here are a few lists to get your creative juices flowing. Please bear in mind that these are suggestions and examples to show off different types of Necron armies and what they can potentially bring to the table. Like any list, they are always works in progress and will be adjusted and improved with play experience .
You Have How Many Shots?! 2k
HQ (680)
Overlord - warscythe, Catacomb Command Barge (180) x2
Royal Court - 4 Harbingers of Destruction, 1 w/ Solar Pulse (160) x2
Troops (740)
Immortals - 5, Tesla Carbines, Night Scythe (185) x4
Fast Attack (310)
Wraiths - 4, 2 w/ whip coils (160)
Scarabs - 5 (75) x2
Heavy Support (270)
Annihilation Barge (90) x3
Total - 2000
This little gem we came up with in Chatbawks. That's 7, count 'em, 7 Twin-Linked Tesla Destructors. That's an obscene amount of firepower that can threaten anything under AV13. To back it up, we have 4 sets of 2 S8 AP2 shots to pick off problem units, 2 swarms of entropic dickery, Wraiths for mop-up/tie down and Barge Lords to act as midfield control or suicide melta.
The important things to keep in mind are that Night Scythes do not function well as gunboats like Rhinos or Chimeras, they act more as attached supplementary firepower. Essentially fitting in more Heavy Support slots by attaching them to Troops units. Also, while the damage output may look sub par on paper, the combination of Wraiths, Scarabs and Barge Overlords gives you a great deal of reliable anti-tank at short range on highly mobile and relatively cheap units. Finally, the overall short ranges are largely mitigated by 2 guaranteed turns of Night Fight as well as the mobility of nearly every unit.
Tut, Tut, It Looks Like Rain 2k
HQ (390)
Imotekh the Stormlord (225)
Royal Court - 3 Harbingers of Destruction, 1 Solar Pulse, 1 Harbinger of Eternity w/ Chronometron (165)
Troops (774)
Warriors - 8, Ghost Ark (219)
Immortals - 5, Tesla Carbines, Night Scythe (185) x3
Fast Attack (310)
Wraiths - 4, 2 w/ whip coils (160)
Scarabs - 5 (75) x2
Heavy Support (525)
Doom Scythe (175) x3
Total - 1999
Imotekh gets touted as an auto-include, which I vehemently disagree with. He's incredibly expensive and quite focused in his application. Night Fight is largely mitigated by turn 2 or 3 as everything will be in range and his lightning bolts are random, so 2 Solar Pulses are a more take-all-comers choice along with the Barge Overlords needed to unlock 2 Courts. The large distinction between Imotekh and Pulses are that Imotekh's Night Fighting applies for both player turns instead of only 1, so you can be hampered as much as you are helped. That's why you need to build around Imotekh. Here we have a large quantity of short ranged firepower and a big focus on midfield control. Death Rays are not effected by Night Fight.
Nemesor Zahndrekh's Big Book of War
HQ (385)
Nemesor Zahndrekh (185)
Royal Court - 4 Harbingers of Destruction, 1 w/ Solar Pulse, 1 Harbinger of Eternity w/ Chronometron (200)
Elites (300)
Triarch Stalker (150) x2
Troops (735)
Warriors - 5, Ghost Ark (180)
Immortals - 5, Tesla Carbines, Night Scythe (185) x3
Fast Attack (310)
Wraiths - 4, 2 w/ whip coils (160)
Scarabs - 5 (75) x2
Heavy Support (270)
Annihilation Barge (90) x3
Total - 2000
Zahndrekh is a big bag of tricks, potentially a big bag of dicks to your opponent. This list sacrifices the awesome tank killing power of 2 Barge Lords and 2 Courts in favor of making everything a tank killing threat. S8 Tesla Destructors, a S9 Court firing out of the Ark, S9 2-shot multi-meltas from Stalkers and that's just Tank Hunters. He also brings out crazy shenanigans and is a pain to put down, making him perfect for giving your objective camper of choice a big boost to survivability.
Derpstar 2k
HQ (570)
Overlord - warscythe, mindshackle scarabs (115)
Royal Court - 4 Lords w/ warscythe, mindshackle scarabs, 1 Lord w/ warscythe, mindshackle scarabs, ressurection orb, 3 Harbingers of Destruction, 1 w/ Solar Pulse (455)
Elites (300)
Triarch Stalker (150) x2
Troops (735)
Warriors - 5, Ghost Ark (180)
Immortals - 5, Tesla Carbines, Night Scythe (185) x3
Fast Attack (105)
Scarabs - 7 (105)
Heavy Support (295)
Tomb Spyders - 2, 1 w/ Gloom Prism (115)
Annihilation Barge (90) x2
Total - 1995
This one is a bit on the silly side, but the Derpstar is something to be feared. 6 models with mindshackle scarabs (average roll on 3D6 is 10.5) can cripple assault units before throwing out a ton of warscythe attacks. They can hijack a Ghost Ark, which is an open-topped transport and go to work. Everything else is focused on controlling the board and giving the 'star plenty of targets to run into.
And we can go on. So, as you can see, Necrons have a lot of new tricks and even something as simple as an HQ swap can drastically change how the army plays. I even played it safe with these, barely deviating from my standard core of Immortals in Scythes and Annihilation Barges. There's plenty out there to find, and I think we'll be seeing all kinds of new and interesting competitive lists out of the Necron Codex. But the only way to find out is to try. In the words of the Cryptek Frizhotep, "take chances, make mistakes and get messy!"
