My gaming days are behind me. I must have played four games of 5th edition and only one game of 6th edition so far. I do buy the rulebooks and read them but I still need your help ironing out the creases of my army list. More after the jump.
This list is made up from models I already own and models from the Necron megaforce. When I used to game with my Tyranids I always went for as many different units as possible. The amount of games I won because my opponents couldn't cope with the target selection. It was also about teaming units up to maximise benefits and this is something I want to do with this army. There is no fun in maxing out on a certain type of unit just to win games. I need the diversity to make painting and gaming fun.

Catacomb Command Barge
This is my unit HQ. I have no idea what to equip him with, so I'll have a closer look at the options later. I'm open to suggestions if you guys have any.

Triarch Stalker - twin linked Heavy Gauss Cannon.
I'm ditching the heat ray for the twin linked Heavy Gauss Cannon. It should be quite reliable being twin linked. It's got a higher strength and longer range then the Heat Ray. The Stalker is a walker so I can move around and shoot, making this an effective tank hunter which is safe from enemy small arms fire.

9 Necron Warriors (one model from existing collection)
9 Necron Warriors (one model from existing collection)
9 Necron Warriors (one model from existing collection)
9 Necron Warriors  (nine models from existing collection)
I've taken the megaforce's twenty four Necron Warriors and split them into three units of eight to paint. I already own twelve painted warriors, so the plan is to combine to make four squads of nine.

10 Necron Immortals (five models from existing collection) - Tesla Carbines
I really want to build these as Deathmarks, but five Deathmarks won't be very effective. I already own 5 painted Immortals, and the thought of expanding this unit to 10 with Tesla Carbines. That should see some nice extra hits and make the unit more effective.

3 Tomb Blades - Particle Beamers, Shield Vanes 
3 Tomb Blades - Particle Beamers, Shield Vanes
These two units will work in concert together. A total of six strength 6 blasts will tear through hordes, and the speed of the jetbikes will allow me to get behind vehicles and and attack rear armour. Splitting the unit creates an extra target for the enemy to deal with and it allows me split up and create problems for the enemy. The shield vans bump the armour save up to 3+.

6 Canoptek Scarabs bases
These bases are beasts, so they move fast coupled with their entropic strike special rule they will be great at softening up vehicles. Being fearless they won't run from a fight so I could use them to tie down an expensive unit for a turn or two.

Canoptek Spyder - twin linked Particle Beamer
With the upgrade this monstrous creature comes in at 75pts. It's relentless so can move and shoot, has the hammer of wrath and smash close combat rules so is useful charging small or weakened units or even light vehicles. However I don't want to rely on it's close combat abilities so I've given it a strength 6 blast weapon which is twin linked. The Spyder's best trick though is generating a scarab base when scarabs are within 6" at the start of the movement phase. I think this will only work for turns one and turn, because the scarabs are beasts and much fast then the Spyder.

Doomsday Arc
Strength 9, AP1, large blast... need I say more? it will make a mess of the enemy's most elite units and vehicles. I will need to use cover and maybe a unit of Necron Warriors to protect this model because it will draw a lot of attention.

Doomscythe (from existing collection)
This unit will be on antiaircraft and anti tank detail. It will first target units that pose a massive threat to my Doomsday Arc.

Necron Defence Lines - Quad Gun
I'm going to scratch build this battlefield terrain upgrade. Foamcore and plasticard and maybe the spare weapons from the Tomb Blades. Should help out against enemy flyers.

Total points is just over 1800pts so I have some points to upgrade my Overlord and maybe add some Crypteks made from conversions of left over bits. Clever use of Crypteks will give my units some upgrades. I like Veil of Darkness which will allow me to redeploy immediately using deep strike. Very handy because my list lacks transports.

I'd really appreciate any advice from Necron players or people that have fought Necrons.