Formations can play a big role in a game of Warmachine. Depending on how you place your unit, it can protect your unit’s back line or screen your caster from LOS and slams. The 2 abilities that benefit the most from various formations are Shield Wall and Vengeance. Let’s first explore Shield Wall formations.
Straight Line
This is the standard straight line formation. It is fairly straight forward, with each MoW standing side by side. One of the biggest benefits of this formation is that it blocks LoS to your caster in the largest arc possible.
W-Line
Next we have the W-Line formation, where the MoW stands besides each other but at in the same rank at intervals. The gist of this formation is that if your opponent does not have reach, he is forced to charge at an angle in order to hit 2 MoWs. The MoWs, having reach, will still be engaged with the enemy.
Spear-tip
This formation totally blocks LoS to (and of) your warcaster but the biggest draw of this formation is that it is flexible enough to be converted into an angled Flying-V formation (more on this later). This allows you to expect a charge on the right or left directions by a slight re-organisation as shown below. The drawback is that your warcaster is dictated by the shield walled unit’s movement speed and he/she does not have LOS to anything besides the sides.
Flying-V
Here’s the much touted Flying-V formation. Due to the nature of this formation, breaking the shield-wall advantage is pretty tedious, if not nigh impossible. It also acts as a 'solid-wall' from jacks slamming into your MoWs, hoping to clip your caster along the way since the back rank of the MoWs will soak up the hit instead. The caster depicted in the pic being B2B with the MoWs are just an exaggeration since your caster can be further back from the wall, as long the wall acts as the barrier.
Mini-V (for single-wound shield walled units)
Shield Wall buffs up a unit’s ARM but let’s face it, they still have one life. A model with a POW 12 gun only needs a -6 on damage rolls against an ARM 18 unit (under the effects of Shield Wall). Worse still, should they suffer the corrosion continuous effect, chances of them living is 1 out of 3. Hence, it is not wise to “brick” them up. Most of these units brick up in a mini-V formation instead. Blast templates would get 3 at most (rather than 5+ if you brick them up all together) and they hit hard as a mini-unit of 3 men. If one dies, the other 2 would still be under the effects of Shield Wall due to being B2B.
The other question that people tend to ask is what kind of formations would you deploy to fully maximise the Vengeance ability?
Mastershake from the PP forums (http://privateerpressforums.com/showthread.php?63232-Vengence-Keeping-your-Elves-angry&highlight=vengeance+formation) wrote up an interesting article which I believe is worth sharing.
Vengeance Formation
“Vengence formations in general are usually spread out and you'll also often models turned at wierd angles to make it exceptionally difficult to charge models in ranks further back without getting free-struck. This forces you to fight a handful of models which means almost the entire unit can get Vengence. It's not a bad idea by any stretch of the imagination to play all Reach infantry formations like this to minimize the damage you'll take from charges, but with Vengence it's how you get the most out of the unit.”
For units with an inherent Vengeance ability, you’d want to spread them out as much as possible like the picture below but at the same time, get your back rank within charge range should the first rank fall apart.
For units with a Granted: Vengeance ability (i.e. Dawnguard Sentinels), you want to spread out the unit too but you need to protect your officer at the same time. The picture below is a good example of how you’d deploy a unit with a granted Vengeance ability. The LOS is well blocked to the officer and the enemy would have a tough time reaching him.
What kind of formations do you tend to use? Any other formations you would like to share?