For
GK squads always aim for Even numbered squads as you are fearless and don't have to worry about
Ld tests. So expanding that squad of 5 to 6 means an extra Marine your opponent has to kill before he is getting points.
When playing a pure
GK army your base Troops choices should be 2 x 6 model
GK Squads with 2 Psycannons. Best all round unit ever. Being able to move and fire with a S6 weapon is brutal and great for popping Transports. However if you don't move them forward the shrouding rolls will drive your opponent crazy which is also fun.
GK Heros in Termie armor can take Psycannons. Termies are always considered stationary. So your
GK Hero can move and still fire the Psycannon with a 36" range. Always take this over Scourging or Psycannon Bolts for your Hero.
Teleport Attack suicide squads. A unit of 10
GKs 2 of which have Incinerators can kill just about anything they drop next to. Eldar hate these. Hell anything that relies on an
Inv save hates these. Even if you don't use them as a suicide squad they make for great psycological warefare.
Justicars with Artificer Armor and an Icon of the Just. Expensive but suprisingly effective. I can't recall the number of times its come down to my Justicar being the last one standing in the squad and holding off a unit in
Hth thanks to a 2+ armor save and a 4+ Invulnerable. Only take these on your
TA squads or anything you are going to bother throwing at the enemy, so not your Troops choices with the Psycannons. Also useful if you give them Melta bombs. Nothing like the look on you opponents face when he finds out the Justicar who just make it into
Hth range with his
LR has Melta bombs.
Purgation Squads with 4 Incinerators + Land Raider = Evil. I haven't tried this before as my
HS choices are usually filled with a
LR and 2 Dreads but in principle this is just cruel. Well less so thanks to
GWs stupid 4th Ed flamer rules but still mean.
GK Termies. S6 I4 Power weapons. Need I say more? And they can always Teleport onto the table. However loading these babies up in a Crusader is your best bet. There are very few things that they will find hard chewing through in
Hth if you get the charge.
And lastly the most important thing to remember when playing pure
GK is to take every chance to praise the Emperor and act like a hero. Odd things happen around
GKs but only if you have faith and are willing to lay everything on the line for that one chance. It not Death or Glory, its often Death AND Glory.
Also be prepared to lose for a bit. It takes a while to really get the feel of how
GKs play but once you do they become insanely powerful.