One of the most significant additions to the Grey Knights codex that was just released is a new HQ option, the Grand Master in Nemesis Dreadknight (abbreviated as GM-NDK from here on). Let’s take a look at his stats, how he compares to existing units (i.e. the “vanilla” Dreadknight), and how GK commanders can maximize its abilities in their army.
First off, the GM-NDK, without any damage, has M8 WS2+ BS2+ S6 T6 W12 A5 Ld9 Sv2+/4++… compared to a “normal” NDK, which has M8 WS3+ BS 3+ S6 T6 W12 A4 Ld8 Sv 2+/5++, the GM-NDK has the same degrading profile (Movement, BS, and Attacks all degrade, based on the number of wounds taken), but has superior WS, BS, A, Ld, and Invul save. Additionally, while the GM-NDK has the same close combat weapon, shooting weapon, and teleporter upgrade options as its “vanilla” NDK, it also comes with the “Character” keyword (so it can be your WL and even take one of the new GK relics), the ability to cast/deny two Psychic Powers (vice just one each for a normal NDK), and the signature Grand Master ability, “Rites of Battle,” which gives all friendly GK units within 6″ the ability to re-roll 1s to Hit.
So, that is a significant set of upgrades over a normal NDK, but what about the cost? Well, the GM-NDK takes a HQ slot, vice a Heavy Support slot, which is generally superior since for almost every kind of detachment you have to take at least one HQ, thus alleviating that “tax” with a very solid HQ choice. Points-wise, without any Wargear costs included, a GM-NDK costs 38 MBs, compared to 26 MBs for a “vanilla” NDK, so it is almost 50% more expensive… that said, if you take into account its superior offensive capabilities, durability, psychic options, and buffing capacity for the rest of your army, I actually think the GM-NDK is almost a steal for its points cost.
As mentioned earlier, the GM-NDK has the same weapons options as other NDKs, including a Gatling Psilencer, a Heavy Incinerator, and a Heavy Psycannon for ranged weapons and either two Dreadfists, a Dreadfist and a Nemesis Greatsword, or a Dreadfist and a Nemesis Daemon Greathammer for close combat weapons. Combined with WS2+/BS2+ and innate re-rolls of 1s to Hit, this make them very dangerous in both the shooting and close combat phases, even when a GM-NDK has moved and so suffers -1 to Hit for shooting Heavy Weapons. Additionally, due to its extra attack over normal NDKs, the GM-NDK has more overall threat potential in assault and can also take more damage back, thanks to its built-in 4++ save.
Now, that we have looked at all that, how can a savvy GK commander maximize the GM-NDK’s effectiveness on the battlefield? Thanks to the new codex, Grey Knights get access to new Relics, new Stratagems, new WL Traits, and an expanded “Sanctic” psychic powers discipline. For the GM-NDK, even though he is a character, there is actually only one Relic that it has access to… the Fury of Deimos, Destroyer of Crys’yllix, Soul Glaive, and Banner of Refining Flame all replace Wargear that the GM-NDK does not have access to and the Cuirass of Sacrifice is “Infantry models only.” This leaves only the Domina Liber Daemonica relic, which forces enemy Daemon units within 6″ to lower their Ld by -1… solid against Chaos Daemon armies, but not spectacular and very situational.
So, if Relics are not really going to enhance a GM-NDK in competitive play, what about Psychic powers? “Smite,” “Purge Soul” and “Vortex of Doom” all give solid abilities to generate Mortal on the enemy and can supplement the GM-NDK’s other shooting options, “Astral Aim,” while a good power for certain uses (such as on friendly GK Land Raiders, Purgation squads with max Psilencers, etc.), is going to be rarely useful on a GM-NDK, which does not want to be hiding behind LOS blocking terrain and instead should be close to enemy lines and/or in melee as much as possible. That leaves “Hammerhand,” “Sanctuary,” and “Gates of Infinity,” all if which are exceptional force multipliers for the GM-NDK. “Hammerhand” adds +1 to Wound rolls for any melee weapons, meaning that, against those high T7/8/9 opponents that it would normally wound on a 3+, the GM-NDK is now wounding on a 2+ in close combat. “Sanctuary” is another obvious buff, giving the GM-NDK in essence a storm shield for a 2+/3++ overall level of protection. Finally, “Gates of Infinity” makes a GM-NDK hyper mobile, with the potential to redeploy almost anywhere on the table every turn if it needs to (and also to escape from close combat and still shoot/charge again that same turn, since it does not have to Fall Back in the movement phase when using this power). The beauty of these three powers is that they all can either be cast on the GM-NDK by itself or cast on it by another nearby GK Psyker (which is almost all the units in the Grey Knight army!)… this means that, potentially, the GM-NDK could make use of all three of these powers in the same turn, greatly enhancing its mobility, protection, and close combat ability all at once.
Aside from Psychic powers from the Sanctic discipline, the GM-NDK can benefit tremendously from some of the new GK Stratagems. Here are a few that can be used to enhance its prowess/effectiveness on the tabletop:
 Truesilver Armour (1 CP) — When a GK vehicle suffers a Mortal Wound, activate this power. For that Mortal Wound and any other Mortal Wounds it suffers for the rest of that phase, on a roll of 5+ they are ignored. Since GM-NDK and NDKs are classified as vehicles, this stratagems gives them the ability to basically ignore 33% of any Mortal Wounds they suffer, which is especially useful in the enemy Psychic phase against opponents that can put out lots of Mortal Wounds via psychic powers (i.e. Tzeentch armies, enemy Grey Knights, etc.).
 Only in Death Does Duty End (1 CP) — This stratagem can be used after the GM-NDK is slain and allows it to shoot or fight one last time for “free” before being removed. While not the best ability ever (the fact that it only works when you are already losing the GM-NDK is a negative), when you REALLY need to take that enemy Warlord with you or shoot to finish off the last man in a unit holding a critical objective, it can make a difference with your GM-NDK.
 Heed the Prognosticars (2 CPs) — While pretty expensive CP-wise, this ability improves a GK Character’s Invul save by +1, so on a GM-NDK it gives it a 3++ (or, in conjunction with a “Sanctuary,” he can have a 2++ which, along with T6 and 12W, makes it VERY survivable against anything but Mortal Wounds).
 Psychic Onslaught (2 CPs) — Another expensive stratagem, but being able to improve the Strength and AP by +1 and -1 respectively for all of a GM-NDK’s Gatling Psilencer and Heavy Psycannon shots for a shooting phase can lead to some VERY potent damage output (i.e. the Heavy Psycannon becomes Heavy 6 S8 AP- Dmg 2 and the Gatling Psilencer becomes Heavy 12 S5 AP-1 Dmg D3)
 Finest Hour (1 CP) — Doubles the range of “Rites of Battle” for the GM-NDK for a turn. Given that the GM-NDK already has a large base (and so a bigger than usual radius for its “Rites of Battle” aura), this stratagem can make it buff most or even all of your army for a turn, if you really need to make sure as many units in your army as possible are re-rolling 1s to Hit.
 Psychic Channeling (1 CP) / The Aegis (2 CP) — I grouped these together because they all either buff the GM-NDK’s ability to cast powers (Psychic Channeling) or deny enemy powers, which are both useful in certain situations, especially when you ABSOLUTELY have to either get a power off or make sure your opponent does not get his power off (don’t forget, you get +1 to casting and deny the witch naturally, thanks to the “Brotherhood of Psykers” rule, so combined with these stratagems you have a very solid chance of “winning the fight” in the psychic phase).
Finally, in addition to Psychic powers and Stratagems, GM-NDK can be chosen as your army WL and take one of the six new unique GK Warlord Traits. Of the WL Traits available, I think the best ones to use on a GM-NDK warlord are as follows:
 Hammer of Righteousness — When the WL charges, he adds +1 to Wound rolls in the Fight phase. If you don’t want to use Hammerhand on the GM-NDK (i.e. to save it for use on other units that turn, or to let the GM-NDK take “Sanctuary” or “Gates of Infinity” as its other “non-Smite” power, then this can be a useful power to give him, though being limited to only after charging has some limitations.
 Lore Master –This allows the GM-NDK Warlord to know one more power from the Sanctic discipline, so basically it can now know Smite and two Sanctic powers. Given that it can cast two powers a turn, this WL Trait gives it the ability to use, say, “Gates of Infinity” and “Sanctuary,” or “Hammerhand” and “Sanctuary” together without outside help, which can be a great addition to your flexibility and combat power for the GM-NDK (if the GM-NDK is running “solo” away from the rest of your army for some reason, then I think the value of this WL Trait goes up significantly).
 Nemesis Lord — Add +1 to the Damage characteristic of your GM-NDK warlord’s melee weapons. This can be a massive boost to your close combat abilities, with Dreadfists now having a damage of D3 +1, Greatswords having a damage of D6 +1, and the Daemon Greathammer having a damage of between 4 and 7. Of all these options, if you are running a GM-NDK with the Nemesis Daemon Greathammer, then I would serious consider this WL Trait, since a minimum damage of 4 (and max of 7) is VERY good and will allow your Warlord to cut through everything from Baneblades to Wraithknights and Imperial Knights with ease.
 First to the Fray — The GM-NDK and all friendly GK units within 6″ get to re-roll failed charges. Given Grey Knight’s proficiency in close combat and the importance of making charges throughout the course of an average game, this is probably the best overall WL Trait and one that most people will use on their GM-NDK, since it provides massive utility not only for your Warlord himself, but also for the units around him as well (using this in conjunction with the “Gates of Infinity” power to escape from combat, then immediately land 9.1″ away from another enemy and then shoot and charge back into combat that same turn will be a very effective use of this WL Trait, I think).
Finally, one thing more thing to remember about the GM-NDK is that it can benefit from certain buffs/support of other nearby characters, such as re-rolls of ALL to Hits if Draigo is nearby, increased Smite range from adjacent Brother-Captains, re-rolls of ALL to Hits in combat from a nearby Chaplain, etc. Perhaps one of the most significant “force-multipliers” for a GM-NDK is actually a Techmarine, since (somewhat surprisingly), all Dreadknights are now classified as vehicles in 8th edition, meaning that they can have D3 of their lost wounds automatically restored each turn by a GK Techmarine within 1″ of them.
Overall, as many players have already figured out on their own looking through the new Codex, I think the Grand Master in Nemesis Dreadknight will be a very competitive, popular, and effective choice in 8th edition, especially when in conjunction with some of the buffs/enhancements discussed above… not only is the GM-NDK a very strong combatant in its own right, but it is a strong force-multiplier to the rest of your army as well, thereby making the entire Grey Knight battle group more effective than the sum of its parts, I think.