In each of these articles we've looked at the major strengths of the Grey Knights codex and how they often appear on the tabletop. What comes out is an army of elite generalists. As individual units they are the equal to or better of nearly every other generalist across the whole game universe and quite often the same is true against other specialists. As an army they work most effectively in the 24" range area where they can avoid being charged but get full use of their weapons and follow up their shooting with effective counter-charges as the game wears on and that 24" distance reduces. This sounds great and down-right awesome all-round but they are of course restricted by extremely high point per model cost. Whilst their vehicles are especially cheap considering the advantages they can gain (+1 strength, 5 points; Fortitude 5 points) their basic infantry models start expensive and get more expensive and this limits and balances them on the tabletop.
Inversely of course there are really cheap options as well in Henchmen units which importantly can be made scoring through Coteaz. This can solve the issue of expensive individual models and a low-model count army but significantly alters the way the army plays. No longer is every unit pretty durable and capable of performing in all situations. Now there are units which are a lot easier to kill and often have a more specialised role.
And this is how Grey Knight army design works. Every Grey Knight unit is pretty similar - you're not going to have a huge variation in terms of what the Grey Knight units actually do. They all have very similar armouries and statlines with weapon options (i.e. 1 per 5, 2 per 5, etc.) and psychic powers separating their roles on the battlefield. I can take units of Strike Squads, Interceptor Squads, Purifiers and Purgation squads for example and never deviate from the Psycannon/Stormbolter mould. On the flip side you have the Henchmen units which can be flexible but are often dedicated to one role such as long-ranged fire support, melta or extreme close combat ability. The balance of both these unit types whilst including other choices such as Dreadnoughts, Rhinos/Razorbacks, Stormravens, etc. will determine how each Grey Knight army plays on the tabletop. They may all look very similar, particularly in weapon loadouts and aesthetics, but even a couple unit swaps can drastically affect their tabletop play.
Again, this all seems really good but there are limitations. We of course here the ever usual whining with all new books but Grey Knights really are limited by their high point costing and like all 5th edition books, you cannot get all your goodies in one army if you want it to be balanced. Beyond this, Grey Knights are primarily a shooting army which relies upon weight of fire. This is great as it's pretty reliable and gives you a lot of bites at the apple. However, against really tough units/tanks (i.e. MEQ with FNP, AV14, etc.) weight of fire can falter. If you need a six to generate damage or rely upon your opponent rolling a few numbers, sometimes it just won't happen. You may have a lot of opportunity to generate those require rolls but sometimes this doesn't happen. This is magnified by the limitation of certain guns within the Grey Knight codex - namely low AP weapons such as plasma guns and anti-tank weapons such as meltaguns. Both of these weapon types can be included within the army and often en masse, but this costs you weight of fire shots and like henchmen, becomes an sliding scale in terms of Grey Knight survivability and specialisation within the army.
There are potential armies you can do which maximise some of these aspects (i.e. Karadread, Coteaz, Purifiers, Interceptors + mass Acolytes) but most armies which try to shoe-horn these type of weapons in en masse will just make a worse Imperial Guard list.
Conclusion
Grey Knights will have a smaller model count to their Marine counter-parts, have very few ranged/melta/low AP options and excel in midfield. They are all about maximising firepower in the 24" range and maintaining that distance for as long as possible and backing this up with counter-assaults based around MEQ statlines and force weapons. Henchmen units can branch outside this to varying degrees with cheaper and less durable models with greater emphasis on specialisation. All this is tied together by cheap and hard to suppress mech and psychic powers/support across the army - though both are not required for the army to work.
All in all an excellent midfield based army with a lot of options in the codex which can look very similar but are impact individual lists to high degrees.
