I'm unsure about costing, but I would perhaps make the following changes:
Relentless Dead: ~ and any Legion of the Damned squad that ~ is attached to gain the Feel No Pain
USR.
Feel no pain is essentially a slightly better version of Reamination Protocols, is simpler, and doesn't steal any of the Necrons thunder or require that players cross-reference rules. Additionally, I would like to see this guy either make
LotD scoring or possibly even a troops choice, since he is a
LotD character. I would tie this into his Chapter tactics. Speaking of which, I prefer Unholy Specters to Flames of Vengeance (since US is good in all situations, whereas FoV is only good against specific codices), but I would change it so that it gives Fearless and changes S&P to Relentless instead. I'd also prefer not to have a wargear duplicate for Vulcan, maybe a plasma weapon of some sort instead, but that is largely just my personal thoughts. I'd also replace the 2+ save with a 3++ due the the Unyeilding Specters rule (which you have forgotten, so I added it). With the changes I suggested, he would look like this:
~
WS: 6
BS 5 S 4 T 4 W 3 I 5 A 3
LD 10
Sv 3++
War gear.
Artificer Armour
Power scythe-relic blade
Heavy flamer gauntlet
Special rules
Fearless
combat tactics
Independent character
Unyielding Specters
Restless dead*
Chapter tactics
Restless Dead: ~ and all Legion of the Damned models in the squad that ~ is attached to have the Feel No Pain
USR.
Chapter Tactics: Unholy Specters
~ is the leader of the Legion of the Damned, and when he appears, the specters appear both in greater numbers and with greater ferocity than usual. All Legion of the Damned units in you army are scoring. Additionally, they gain fearless and replace the Slow and Purposeful
USR with the Relentless
USR.
Costing: