Where the Immortals are the Necrons' Shock troopers who supply heavy fire power, the Deathmarks bring elite, surgical threat removal to the board. Sixty million years ago, when the Necrontyr were still made of meat and blood, the Deathmarks did more or less exactly what they do now: appear from the shadows, kick the fuck out of their target, and then leave. The Deathmarks received high-quality shells during bio-transference, and thus have remained largely unchanged through the millennia. But military honor tradition among the Necrontyr impose harsh restrictions upon the deployment of Deathmark squads. Among each other and any 'honorable' alien opponents, Deathmarks are taboo. But most Overlords see other races as ignoble and inferior, so few balk at the idea of deploying the assassins, except for Nemesor Zahndrekh; the crazy old coot won't use Deathmarks against anyone, because they're all Necrontyr to him.
Also their guns cause a target's molecules to explosively repel each other. Don't like that dumb new primaries fancypants? Turn his forehead into a bomb.
Deathmarks don't need to deploy to the field of battle with the rank and file; instead, these cyclopean laser-rapebots spend their time in the inter-dimensional break room watching their intended target on 4-dimensional wide screen monitors and doing fuck all until the commander summons them, or whenever the fuck they feel like doing something. Typically they are left to their own devices, the nobility having great faith in their long practiced art of death. Once it's time to get shit done, they place a hovering green halo of light on the head of their target or targets, thus the name Deathmarks. This mark lasts about one hour, but given their dimension-hopping abilities that's usually more than enough time.
On the tabletop, Deathmarks are your long-ranged infantry standard (sorry destroyers, not this edition), serving up character-exclusion zones and supporting fire. Don't sleep on them; unlike earlier editions Deathmarks are now priced to move, and they're just as tough as immortals. Their secret sauce is a deep-strike: vanilla, where you drop them on some objective and start cracking BS 2+ shots at some poor devastators, or delicious chocolate, where they appear in response to an enemy deep-striker and start dropping fools in the enemy's movement phase. Warning, this doesn't work against space marine drop pods; against GW's precious little snowflakes you're forced to fire at the pod rather than its cream filling. But anybody else, especially some low-wound high-save specialists? Food.
- Hexmark Destroyers, Deathmarks that have succumbed to the Destroyer curse