Since I have a soft spot in my heart for Grey Knights, I continue to look for ways to run them competitively, especially so they can have an option besides “cram as many Dreadknights into the list as you can and pray for the best.”
Based on this, and looking back at the new Angel’s Blade supplement for Blood Angels faction, I think a potentially solid ally for a Grey Knight army is the new Lucifer Armoured Task Force Formation. This formation requires the following:
-3-5 squadrons of Predators or Baal Predators
-1-3 Land Raider/LR Crusader/LR Redeemer
In exchange for taking these units, all vehicles in the formation get Scout and become Fast Vehicles for free (even including Land Raiders!). This is obviously a very significant bonus, even when this formation is operating alone, but used alongside a Grey Knights force I think it really brings some tremendous benefits. Specifically, consider the following Lucifer Armoured Task Force:
-Techmarine with Servo Harness
-3 x individual Predators with triple Lascannons
-Land Raider Redeemer with Extra Armor
I think this formation provides several things to a Grey Knight primary detachment: first, Grey Knights generally lack long-range anti-tank/anti-MC shooting, outside of Razorbacks, shooty Dreadnoughts, and Land Raiders with Lascannons. This Predators in this formation not only have Scout, giving them a free 12″ move before the game to get into firing position, but being Fast Vehicles, they can move 6″ and shoot all their weapons at full BS (or move 12″ and shoot two of their Lascannons at full BS), which makes them excellent, affordable “Lascannon gunboats” in support of a Grey Knight force. With a 6″ move and a 48″ range on the Lascannons, plus the pre-Game Scout move, they can threaten almost any enemy unit turn 1. This is especially useful for taking on enemy Wraithknights, Stormsurges, TWC, Hive Tyrants, not to mention tanks/transports, at long-range, before they can deal much damage to your Grey Knights. Finally, this synergizes quite well with the shooting/close combat threat of Dreadknights shunting up-field Turn 1 and infantry from a Nemesis Strike Force DSing in turn 1.
Secondly, the LR Redeemer (with Techmarine riding inside for repairs) provides an excellent “taxi” for a squad of Purifiers armed with massed Incinerators. While the Purifiers cannot start the game inside the LRR (and thus cannot benefit from the Scout move), they can load up turn 1, then have the LRR move 12″ and Flat Out another 12″ for a net movement of 24″ before the end of the first game turn. This sets them up for a very reliable turn 2 disembark, Cleansing Flame in the Psychic Phase, Incinerator/Flamestorm Cannon templates and the TLed Assault Cannon in the shooting phase, and charge in the Assault Phase with NFW/Hammerhand, which should be pretty devastating to many opposing armies due to how many mass wounds this can generate, especially against large enemy units. The ability to displace 24″ a turn, and then move 12″ and still shoot all of its weapons (Fast Vehicle status means it can shoot two weapons at full BS and POTMS means it can shoot a third weapon at full BS as well) makes the LRR from the Lucifer Armoured Task Force significantly superior to a “normal” LRR available to the Grey Knights army. Finally, if you don’t want to use it as a transport for GK infantry, then you can have the LRR Scout up 12″, then move another 12″ and hit units in the enemy DZ with dual S6 AP3 templates on turn 1, which also synergizes quite well with the “in your face” approach of many Grey Knight armies.