Necrons ARE NOT Our Friends

[ContemptuousAngel]

Also target priority is a big deal. Ghost Arcs need to be destroyed first. They have a very powerful weapons array, are open topped transports allowing the warriors inside to fire as well, and can rebuild the things you've managed to actually kill. 

Monoliths need to be dealt with now, but a close combat DC or Furioso dreadnought can handle that just fine. Make sure you kill it dead. Those things are not fun if they get to fire or teleport your opponent's army around the table. 

Unfortunately their flying transports do not fall prey to crash and burn. The necrons inside are not actually inside the ship. The ship is basically a flying teleportation pad. So by all means kill it, but know that the guys "inside" are just going to come on the table from ongoing reserves. More of an inconvenience than anything else. 

Pariahs die to templates easy. They killed a squad of Death Company handily and then were annihilated by a frag cannon, heavy flamer, assault from a furioso as though they were paper people. 

What else... 

Tomb Blades. The thing that GW designed Decurion Formation in order to sell. They are not very good for jet bikes. They die easy. Unfortunately killing them does not take away that +4 RP save.

Immortals: I've lost squads on overwatch from these guys. Full squads. Horrible. Soften them up a lot first, but with their shooting and high AP weapons they are a high threat.

I haven't faced the Necron close combat maniacs yet.

Destroyers: DIE VERY EASY IN ASSAULT. It's worth assaulting them with a regular assault squad. More chance of killing them off on your opponents turn so that you don't lose the squad from return fire. Or multi assault. My necron playing friends stopped bunching their destroyers together because I would just multi-assault them with sanguinary guard and they'd lose both squads in one turn.

Triarch Stalker: Probably higher priority than anything else. Gives a BS 5 bubble to everyone around it??? Nope. Kill it. Then stomp on it and set it on fire. 

 

I'm probably missing a lot of things but these jumped up to the forefront.

[IK Viper]

Grey Crow just wanted to make everyone aware that the ReAn goes off immediately after saving throws are taken in the same manor as a FnP save.  You cannot negate this save except with D strength weapons.  Instant Death inflicts a -1 penalty to the ReAn save though.  Sadly this makes winning combat with Necrons by enough to actually sweep them very hard because unlike before with the old book, the unit gets to make ReAn rolls before combat resolution occurs. 

 

The old tactic of "kill everything in the unit," so they don't get a chance to get back up no longer applies either, they will get their ReAn no matter how many armor saves they fail. 

 

You should essentially treat and think about a Necron as having a rerollable save in most cases.  a Warrior gets a 4+ armor and a 4+ ReAn if using the Decurion Detachment, which I suspect you will see mostly.  I have no answers to this hyper durable army.  I honestly think the GW game designers do not understand how powerful a rule they created and that Necrons will quickly be recognized as a new Tier 1 army in the same realm as Tau, Eldar, and Daemons.  Pretty much blows the whole "we are toning the 7th ed books down," idea... 

 

To beat them with BA you need to beat them with speed and by dismantling them in a set order.  Go after their vehicles and fast movers to limit their board presence.  Then go after the durability buffers in the army, things that restore models to the game such as Ghost Arcs, Canoptic Spiders, and also the Warlord.  In the Decurion Detachment, one of the many free rules they get is the ability to reroll ReAn rolls of a 1 on units within 12 inches of the Overlord purchased in the Reclamation Legion formation (the required formation of Warriors, Immortals and Tomb Blades) 

 

You really need power weapons to clean up the infantry quickly.  I would send my Power Weapons after their infantry and send my Assault Squads after the (now even better than they already where) Wraiths.  ASM give weight of attacks which is want you need to kill Wraiths.  Sang. Guards do a decent job with their infantry but their lower number of power weapon attack is largely wasted against Wraiths.     

 

Also, honestly the mission need to be right in order to have much of a chance.  If someone parks 40 warriors on the Relic in cover, the game is basically over.  Not sure why GW allowed this to be the case but it is pretty much the truth.  TO have a fighting chance against Necrons the mission needs to have 3 or more objectives  and you want them spread out all over the field to abuse the relative slowness of the Necron army.

 

Going 2nd and jumping in at the end of the game with ObSec units is probably your best bet to beat them.    

[IK Viper]

I would add that is has been my limited experience that BA armies benefit a lot from the Biomancy Discipline.  Enfeeble in particular should be used to really help focus units down.  Enfeeble is a great way to deal with Wraiths since you can now double them out with S8 like you used to be able to.  Also it is much easier to overwhelm them with wounds when you are wounding on 4's or 3's if you charge them.  

 

I suggest Biomancy against Necrons. 

[ContemptuousAngel]

I just default to biomancy because almost every power is useful, and the Quickening is IMO the best power in the game.