My suggestion, unfortunately, will be a particularly unfluffy one. In order to win a mission of annihilation one need not obliterate the entirety of the opposing force. All it takes ruleswise is killing one unit more than you lose...
For that reason, Annihilation is probably the easiest of the standard missions for Necrons to win. They have only few units, and those which they do have are quite tough and durable. Moreover, most armies have transports while the Necron do not. This may appear to be a disadvantage -which generally it is- but in this case it turns to an advantage: transports are easy targets and quickly killed, awarding easy kill points - a vulnerability Necron forces do not share. Thus it is very hard for opponents to score kill points against Necron armies...
The tactic i usually suggest for annihilation is to snipe weak targets and spend the rest of the game in hiding or flight once you are ahead in score. It is unfluffy, but very effective. Towards this aim, destroyers are (as I keep saying at just about every occassion, my apologies for that) the best choice. They can engage the enemy at range, thus not taking too big a risk, while their enormous firepower will take out weak targets reliably, and their awesome mobility grants them the ability to withdraw in time to avoid serious retaliation.
I would not suggest advancing your phalanx. Try to keep safe and in hiding, avoiding dangerous assaults and close-quarters engagements while sniping kill points with your long-range guns. This is -of course- not a viable tactic against barrage-heavy Imperial Guard builds, for example, where hiding is futile and being at a distance is a huge drawback. In this case a head-on assault is certainly the better alternative.
Deploy your main force packed tightly together, maybe split the destroyers off to march them up on a flank so as to be able to target side armor, but the more compact you are the better.
The monolith, of course, is a very good choice against most opponents as well: hard to take down, good to protect your army, able to snipe weak targets at decent range.
For that reason, Annihilation is probably the easiest of the standard missions for Necrons to win. They have only few units, and those which they do have are quite tough and durable. Moreover, most armies have transports while the Necron do not. This may appear to be a disadvantage -which generally it is- but in this case it turns to an advantage: transports are easy targets and quickly killed, awarding easy kill points - a vulnerability Necron forces do not share. Thus it is very hard for opponents to score kill points against Necron armies...
The tactic i usually suggest for annihilation is to snipe weak targets and spend the rest of the game in hiding or flight once you are ahead in score. It is unfluffy, but very effective. Towards this aim, destroyers are (as I keep saying at just about every occassion, my apologies for that) the best choice. They can engage the enemy at range, thus not taking too big a risk, while their enormous firepower will take out weak targets reliably, and their awesome mobility grants them the ability to withdraw in time to avoid serious retaliation.
I would not suggest advancing your phalanx. Try to keep safe and in hiding, avoiding dangerous assaults and close-quarters engagements while sniping kill points with your long-range guns. This is -of course- not a viable tactic against barrage-heavy Imperial Guard builds, for example, where hiding is futile and being at a distance is a huge drawback. In this case a head-on assault is certainly the better alternative.
Deploy your main force packed tightly together, maybe split the destroyers off to march them up on a flank so as to be able to target side armor, but the more compact you are the better.
The monolith, of course, is a very good choice against most opponents as well: hard to take down, good to protect your army, able to snipe weak targets at decent range.
