Wraiths

Wraiths have a 3+ invulnerable save. When attacking models in or behind cover, Wraiths count as having frag grenades so will strike simultaneously.

Wraiths move in the same manner as jetbikes but they regard no terrain as impassable and never have to take Difficult Terrain tests. Wraiths cannot end their move "inside" objects to avoid being shot at. They cannot move through enemy models or vehicles either.

If a Necron army is reduced to 25% or less of its original number of models with the Necron special ability. it will disappear in an eerie fasion, leaving behind nothing of its presence. This gives an automatic victory to the enemy, regardless of the victory conditions of the scenario being played. Do not include C'tan, Pariahs, Scarab Swarms, Monoliths and Tomb Spiders towards the number of destroyed models or the total original size of the army.

Any model with the Necron special rule that is reduced to 0 wounds, or would otherwise be removed as a casualty, is instead laid on its side to show that it's damaged. At the start of every Necron turn, damaged Necrons with 6" of a model of the same type may self-repair. On a roll of 1-3, remove the model as normal. On a 4-6, the Necron is repaired and stands back up with 1 Wound remaining and joins the closest unit of the same type. 
A model cannot self-repair if it was destroyed by a close combat weapon that allows no Armour saves or any weapon whose Strength is twice the Toughness of the Necron. Models destroyed due to a failed 'Death or Glory' attack may not be repaired by any means.
Necron Lords do have need to have another model with 6" in order to self-repair.