Here are some quick Grey Knight 500 point army lists.
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List One - Terminator foot-sloggers
HQ: Brotherhood Champion (100 pts)
Troop One: Terminator Squad (4x Nemesis Force Halberds and Justicar with Daemon Hammer) (200 pts)
Troop Two: Terminator Squad (4x Nemesis Force Halberds and Justicar with Daemon Hammer) (200 pts)
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List Two - Purifers
HQ: Castallan Crowe (150 pts)
Troop One: Purifer Squad (Knight of the Flame with Master Crafted Daemon Hammer) (130pts)
Troop Two: Purifer Squad (5x Nemessis Force Halberds) (130 pts)
Dedicated Transports: 2x Razorbacks (90 pts)
Notes: not a fan of the purifers, but a tidy little army with a bit of mobility.
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List Three - Grey Knight only; Maxing models with some movement options
HQ - Brotherhood Champion (100 pts)
Troop One - Grey Knight Strike Squad with Psycannon (110 pts)
Troop Two - Grey Knight Strike Squad with Razorback (psybolt ammunition) (150 pts)
Troop Three - Grey Knight Interceptor Squad with Justicar with Nemesis Daemon Hammer (140 pts)
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List Four - The Spanish Inquisition
HQ - Inquistor Coteaz (100 pts)
HQ - Ordo Malleus Inquisitor with Hellrifle (40 pts)
Troop One - 7x Death Cult Assassins and 3x Crusaders (150 pts)
Troops Two - 6x Psychers (60 pts) (Note! --> Psychic Barrage: range 36"; Str 8; AP 1; Assault 1, Large Blast)
Troop Three - 3x Inquistorial Servitors 2x Heavy Bolters; 1x Plasma Cannon (40 pts)
Dedicated Transports - 2x Inquistorial Chimeras (110 pts) for troops one and two.
Put Ordo Malleus Inquisitor with the servitors. The Chimeras are open topped vehicles, so troops can fire from them.
Note: Ordo Xenos Inquistor with Conversion Beamer (70 pts) is a very interesting option. Troops two and three could be combined into one troop.
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List Five - Grey Knight only; Mix and Match
HQ - Brotherhood Champion (100 pts)
Troop One - Grey Knight Strike Squad (100 pts)
Troop Two - Grey Knight Terminators (4x Nemesis Force Halberds and Justicar with Daemon Hammer) (200 pts)
100 pts left.
Could use these points to turn HQ into a Librarian (150 points plus some extras for Psyker abilities; Digital and Master Crafted Weapons) and a Psycannon for the Strike Squad.
Could use them to turn the HQ unit into a Grey Knight Grand Master (175 points) with some upgrades.
Could add Justicar Thawn (75 pts) to the Terminator Squad
Could use them to get a Razorback Transport for the strike squad.
Not a compelling list. the problem with trying to get terminators in an army list of this size is that they end up foot-slogging it.
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List Six
HQ - Brotherhood Champion with Digital Weapons (105 pts)
Troop One - Grey Knight Strike Squad with Psycannon (110 pts)
Troop Two - Grey Knight Strike Squad with Justicar with Nemesis Force Halberd (105 pts)
Heavy Support - Dreadnought with 2x Twin-linked Auto Cannons (Range 48"; Str 7; AP 4; Heavy 2) and Psybolt Ammunition (+1 Str) = 4x twin linked Str 8 shots (135 pts)
Dedicated Transport: 1x RazorBack (45 pts)
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Other thoughts and tasty choices:
A Razorback with Twin-Linked Assault Cannons and Psybolt Ammo (Range 24"; Str 7; AP 4; 4 Heavy, Rending) for 85 points seems very tasty. Taken with a Standard Grey Knight Troop choice; 185 points.
There seems to be little worthwhile value for points upgrades to the standard troop choice of GK Strike Squad.
The Terminator Troop choice with 2x Nemesis Halberds and 2x Demon Hammers and Justicar Thawn (275 pts).
Heavy Support - Dreadnought with 2x Twin-linked Auto Cannons (Range 48"; Str 7; AP 4; Heavy 2) and Psybolt Ammunition (+1 Str) = 4x twin linked Str 8 shots (135 pts)
Nemesis Dreadknight with Nemesis Great Sword and Personal Teleporter and Gatling Psilancer (240 pts): 30" teleport and moves like jump infantry (12").
Grey Knight Inceptor Squad with 4x Nemesis Halberds and Justicar with master crafted Dameon Hammer (155 pts). Again with the 30" teleport and jump infantry movement.
