Anti- WraithWing Army!!! Help!!!

Recently at my local hobby store a new necron player has shown up using an army which is just...

1850
HQ: Overlord
Troops: 12 Warriors in a Night Scythe
12 Warriors in a Night Scythe
FA: 6 Wraiths w/ something that makes me initiative 1
TIMES 3
HS: 3 Tomb Spiders
TIMES 3

Ok, I know DE should be good at killing an army which has high toughness models but the problem is when you focus on the spiders the wraiths murder EVERYTHING and when you focus on the wraiths the scarabs which the spiders spawn destroy your vehicles and later on in the game you just die. is their anyway of beating this without using hoards of wracks and venom spam?! I have access to an eldar farseer, 10 gaurdians and a wraithknight which i now know gets mauled by wraiths. Generally I would focus on the 2 warrior squads but apparently the occupants are put immediately into ongoing reserves (suspicious) and eventually just come onto the table by the time everything I have left is fighting is uber assault stuff. Help would be highly appreciated!!!

Just to double-check, that's 3 units of 3 Canoptek Spyders?

I don't know what models you own, but your game plan is to try to do as much damage as you can before the Night Scythes arrive. They are flyers and they transport the Warriors so they won't be on the board at the beginning of the game. After that you have to deal with the Wraiths and the Tomb Spyders. The Overlord should be a Destroyer Lord and join the Wraiths, but if he's actually an Overlord then I don't know where he'll be.

So the big concern is the Wraiths which move 12", can re-roll assault moves and are S6 rending in melee. Direct all of your Dark Lances and Blasters at the Wraiths first because it will cause Instant Death and remove a lot of Wounds at once. It's best if you're fully mechanized so you can kite the wraiths to some degree while shooting. If you can manage the Wraiths without taking too much damage then you've probably won.

After you kill the Wraiths, use Dark Lances against the Flyers as they come in and shoot Splinters at Tomb Spyders. Try to avoid melee because the only shooting he has is in his Troops choices. He only has two units of Warriors, and don't be afraid to dump your shooting at them if they deploy from the Night Scythes because it will limit his ability to score objectives.

In the end, he's going to try to use his Spyders to try to contest your objectives while claiming his with Warriors. You can shoot the Spyders, but you're just as well to ignore them if you can because they're harmless if they can't assault.

As far as what to bring, I would recommend a lot of Venoms and Ravagers. Boring, but effective. DE have a pretty easy time against Cron lists like these and the boring list is what does it best. Any deviation from the basic list should bear the goal of kiting and shooting Wraiths in mind. You don't need to kill the Night Scythes to win the game and he might need to deploy his Warriors before turn 5.

Number 1: Units that are inside Night Scythes aren't put into ongoing reserves, but normal reserves, so still have to be rolled for. Of course they will still arrive automatically at the start of turn four or later. (Well technically, by RAW they will never appear, after turn four, being trapped in reserves eternally, but let's just not go there.)

Number 2: Canoptek Spyders can't, contradictory to their fluff text, actually create Scarab units. They can only add a base to an existing swarm.
If you like the player and would like a friendly game with him, tell him before the next game. He'll probably change his list to contain a swarm of Scarabs, but then you'll only have to worry about one swarm and his spyders will have to bunch up within 6" to add new bases and those can only be created, if they can be put into coherency (aka 2") of a base, that hasn't been created this turn, so he'll run out of space rather quickly and can't run his Scarabs too far ahead. So less Scarabs and less Wraiths for your opponent and for you to deal with.
If you should not like this particular player and would rather not play against him ever again, tell him mid game. He'll probably never even talk to you.
Regardless which route you take make sure to print the Necron FAQ, before your next game.

Against Wraiths:
There are two ways for you to deal with them.
a) Drown them in splinter fire. Wraiths are T4 3+ 2W models, or glorified SM, so 6 Wraiths are the equivalent of 12 Marines. If he equips them with whip coils they should have no shooting at all, even if some have the ranged options, they are only range 12", so kite them with your vehicles. Jump infantry can either move 12" or re-roll charges and do HoW, so keep them at bay while plinking away and when in doubt move flat out, rinse and repeat. The board shouldn't be too packed.
b) Dark-Light them away. S8 will instagib them, so now they'll only equal 6 Marines, doesn't sound to bad anymore, does it?
In both cases, what does rending get him? Against Infantry he'll be AP2, it's not like we rely on armor  anyway. It doesn't even ignore FnP anymore, which you would loose on any T3 model, anyway. Against vehicles he'll get an additional D3 for his AP roll. Not that an AP roll of 6 would be a penetrating hit to begin with. Keep in mind that rending hits against vehicles are not AP2, so no +1 on the damage chart.

Against Spyders:
They are rather basic MCs, but actually again glorified SM. Their T6 doesn't count anything against splinter fire and won't really help against Darklight either. Yes, no instant death but you'll still wound on 2+. Their 3+ save isn't scarier than standard Marines either. 3 Spyders are 9 Marines, not scary at all, if you ask me. If he wants to create Scarabs, he'll have to concentrate around the existing Scarab units, so he'll probably end up in a blob of some way, just evade him and again, when in doubt move flat out, rinse, repeat.

Against Scarabs:
If he overstretches and you can bind them in assault, without fearing retaliation from spyders or Wraiths, do that. They are WS2 S3 and their entropic strike won't hurt 1 Wound models, and even if it would, again who cares about armor saves. Maybe don't throw Incubi at them, but everything else is fine.
But their biggest weakness is actually the swarm special rule. They double unsaved wounds from every Blast, Large Blast or Template Weapon. Liquifiers are good against them, but we can't field too many of them and will be very vulnerable to a counter-charge, so they might not be the best way. But a razorwing with Monoscythes. S6 AP5 Large Blast. That's a Scarabs nightmare. 2+ to wound, every wound unsaved and doubled plus instant death, so every wound removes one complete base. They'll evaporate, before your opponent can start to cry.
Hell, even Shredders will actually shred them. I don't think they are worth anything, but I might just be tempted to use a unit of Shredder-born, just for fun.

Against Scyths:
Ignore them as much as possible. Their Tesla-Destructors are dangerous, but only 24", additionally he has to measure from the gun Barrel, that should cost him some inches, too. If you bring a Flyer, some other AA and/or a Farseer with Prescience, Guide and/or Doom you can try to bring them down, but they are not the worst threat you face and the occupying Warriors will have to disembark to claim any objectives.

Mechanise, run away a lot and target priority.
The wraiths are your priority.
Their 3++ means weight of fire matters mostly, although lances will ID
A Venom will kill 1.33 wraiths, a Ravager, 1.111

1500pts?
6 Venom and three Ravagers will kill the wraiths in two turns.
Turbo Turn three to get your forces clear of the enemy, dont be afraid to sacrifice a couple to save the rest

You cant ID the spiders, but they dont get a save against lances, so wont survive two turns either. Although you may not even have to kill them, if you can, run.