Atomiser Beam Lance
The Atomiser Beam Lance is the primary and ONLY ranged weapon for the Canoptek Reanimators. Not much is really known from this weapon other than the fact that it can disintegrate its foes...which isn't really telling much since every Necron weapon disintegrate their foes.
So whether it is a form of Gauss, Particle or Enmitic Weapon, we have no fucking clue. However, it could also heal back downed Necrons, so it might be some sort of molecular manipulator. It does have four orbs of doom however, so it at the very least has a good rate of fire.
Crunchwise, the Atomiser Beam Lance is a really short ranged (As in 12") Assault 3 weapon, that is S6, AP-2 and deals 1 Damage each. For something of such size, it is severely underpowered and undergunned which is surprising given the modus operandi of Necrons assblasting their way through anything into oblivion. Nevertheless, this weapon is also a part-time Narthecium, as it has this special rule called Nano-Scarab Reanimation Beam: which, in your Command Phase, you can select one friendly Dynasty unit within 9" of this model. If you do, until the start of your next Command Phase, while that unit is within 9" of this model, add 1 to Reanimation Protocols rolls made for models in that unit.
Given that the Reanimator is a support unit, it would be given that the Atomiser is focused in cleaning up GEQs, but its crippled short range and underwhelming statline puts the Reanimator in an awkward situation.