For one, you may want to split the Immortals into two groups. It will cause you to have another KP, but it will be far harder for your opponent to kill.
The other problem I have, and a far more serious one, is your fast attack. Necrons need redundancy to excel, because it means it is harder to wipe all of that model out in one turn, which means you will almost always get WBB. Your fast attack so far has no redundancy. Due to costs and likely available models, I would suggest you drop the Wraiths and use the points to add 2 more Destroyers, then split the Destroyers into a squad of 3 and a squad of 4. Wraithwing is fantastic, but doesn't work very well with only three Wraiths.
If you decide to drop the Wraiths and add Destroyers, make the Lord a foot Lord to give res. orb to you warriors, the Destroyers are too high of T to need it. If you can't afford this option, keep the D. Lord, maybe give it Lighting Field, and have the Scarabs, Lord, and Wraiths run together.