Necron Decurion Math-hammer 2 - Wraiths with Resurrection Protocols

Wraiths are hard to kill already, with 2 wounds, toughness 5 and a 3+ invulnerable save. It takes a lot to kill them in their standard state. What happens though when you have them in a Canoptek formation in a Decurion detachment. Madness, thats what happens. Here is the maths behind killing wraiths when they have a 3+inv save and 4+ RP.

Shooting the wraiths with Bolters from Marines

2/3 shots will hit due to BS of 4
1/3 hits will wound due to T5 vs S4. So 1/3 of 2/3 is 2/9 of shots will wound.
1/3 of wounds will fail their save. So 1/3 if 2/9 is 2/27 will fail their save.
1/2 of failed saves will fail their RP roll of 4+. So 1/2 of 2/27 is 1/27.
It will take 27 bolter shots to do 1 wound to a wraith!
To kill a full squad of 6 wraiths, it will take 162 bolter shots. Broken much??

Shooting the wraiths with Krak missiles from Marines

2/3 shots will hit due to BS of 4
5/6 shots will wound due to S8 vs T5. 5/6 of 2/3 will be 5/9 shots will wound.
1/3 of wounds will fail save of 3++. 1/3 of 5/9 is 5/27 shots will fail save.
1/2 of failed saves will fail their RP roll of 4+. 1/2 of 5/27 is 5/54 of shots will actually cause a wound.
It will take 10.8 Krak missiles to cause 1 wound on a wraith! 
To kill a full squad of 6 wraiths, it will take 64.8 Krak missiles.

Killing wraiths with S10 hits (for Instant Death bonus)

I won't start with a BS skill here due to S10 being rare and a variety of different BS of its users.
5/6 hits will wound due to S10 vs T5
1/3 of wounds will fail save due to 3++. So 1/3 of 5/6 is 5/18 of hits will fail save.
2/3 of saves will fail RP due to -1 to RP rolls because of instant death. 2/3 of 5/18 is 5/27.
It will take 5.4 S10 HITS to KILL a wraith.
To kill a full squad of 6 wraiths it will take 32.4 S10 hits. Remember these are hits not shots, you have to factor in BS skill and/or blast scatter first. With a guards man BS of 3 you will need to multiply this by 2 to account for only 50% of his shots hitting.


So basically wraiths are nearly impossible to kill by simply shooting them with guns. They do however have a big weakness. This formation requires a single Canoptek Spyder (Tomb Spyder in old money) to give the formation RP rolls and it needs to be within 12". Either kill the spyder or somehow force the the wraiths away from the spyder. The spyder has to be by itself, not a squad of 2 or 3 spyders, so it is quite vulnerable but it will also have RP too, so T6 with a 3+ save and 4+ RP rolls will also be quite hard to kill. And don't forget the scarabs in the formation will also have 4+ RP rolls, which is just funny.

Necrons as a whole seem stupidly resilient with the Decurion, but seeing things with a 2++ re-rollable save I don't feel too bad about this. While our army is hard to kill, we don't put out that much damage and this (sort of ) balances things out a bit.