Royal Warden

The other Emperor's Companions.

The Adeptus Custodes of Necrons.

Royal Wardens are Necrons who serve directly under an Overlord and ensure their lord's will is carried out by the Dynasty's armies and are clearly a step above your typical Lychguard.

Royal Wardens possess the initiative to adapt on the battlefield and can modify the orders to phalanxes of Necron Infantry. While they retain an independence of thought, their command protocols still make them unquestionably loyal. Royal Wardens are armed with Relic Gauss Blasters and wear a cloak of Sempiternal Weaves on their left arm and shoulders (Although the crunch does not denote that). Despite their formidable combat prowess, however, Royal Wardens also have direct influence over his underlings due to his close connection with his Lord. This makes him just as much as an adept commander as he is a warrior.

Crunch

At last, the Necrons have their own Primaris Lieutenant. He is a support character with a relic gauss blaster (Rapid Fire 2 and D2 compared to the base Immortal). His Relentless March grants a <DYNASTY> CORE unit +1 to its Move characteristic. During the command phase, he can let a <DYNASTY> CORE unit within 9" fall back and remain able to shoot and charge. This can seriously boost the effectiveness of a large blob of Warriors or Immortals; while they have a Royal Warden nearby, their relatively-short-ranged shooting can't be turned off simply by being charged. This guy got even better with a 2021 rules update that gave CORE to most of the good melee units; now your heavy hitters can pull the Wraith trick.

The main drawback is that Necron HQ slots are extremely competitive due to the Crypteks and unique characters, so an army that doesn't absolutely need to keep a critical unit from getting stuck in melee is usually better served by going with something else.

If you're a Mephrit boy, you gain the Conduit of Stars relic. This is a direct upgrade for the Royal Wardens' gun with +1 strength +6” range and +1 base shot. (S5 AP-2 d2, rapid fire 2, 30” —> S6 AP-2, d2, rapid fire 3, 36”). Voltaic Staff is often a better upgrade but there is the meme of getting 6 shots instead of 2 at 15-18 inches.