The tombships of the necron fleets are monstrous in size and extremely well armed. While not as agile as smaller vessels, they are still able to quickly accelerate to speeds that many vessels of the Imperial Navy cannot match. The sight of one bearing down has paralyzed many ship's crews into inaction, even as mass teleporter arrays activate and the decks are flooded with mechanical nightmares.
Good for BFG or other, inferior, space games. Not found in Epic Armageddon, I guess the list creators assumed if the tombship got to orbit then there was no need to play things out on the ground.
