Defining units in 40k

Thesis

It's very comfortable for us; 40k players find it simple to call a Space Marine Terminator 'heavy' and an Imperial Guardsman 'light'.

Heavy Infantry?

To truly define a unit in 40k, however, we must consider its potential and its roles. While an Assault Terminator definitely has more survival potential than a Tactical Marine, it is noticeable that in an actual game, an Assault terminator will cover more ground and thus, cannot simply be defined as 'Heavy' or "Superheavy".

There are four things that must be considered when defining a unit and its capabilities

Role

Mobility

Armour

Statline

In detail:

Role

A model or unit's role refers to it's duty on the battle field, what a the player ('Commander') wants it to do.

Mobility

A model's mobility is literally defined by the speed at which it normally moves, and how it may move and still be effective.

Armour

A models armour is well understood to define its typing. Most  can be content to ignore role and mobility, and simply see "oh this guy has a cool 2+3++ save! He's a Super Heavy Infantry!"

Statlines and quantity/value:

Statline refers to the characteristics of each model inherently.

While usually only its Toughness and wounds are considered, a model’s Leadership, strength, attacks and skills can also play a vital role in deciding a model’s characteristic value.

Producing a definition

With these four terms in mind, it becomes a much less clear and clean-cut definition of ‘heavy’ and ‘light.’

To produce a definition, it is usually the case that a unit’s four emphasis points will be given a ‘weight’. For example, a 2+3++ save is almost always considered superheavy. But, the name superheavy automatically implies that the unit is slow; this is not always the case.

So then we have to look at the other four points of the model with a 2+3++. If you’re thinking like I am, the most prominent example of a 2+3++ would be an Assault Terminator

The 2+3++ dilemma

An Assault Terminator can be defined in four points

1. It has a 2+3++ save. (Superheavy)
2. It wants to move very quickly, but can’t. (Medium)
3. It wants to close into assault with hard-hitting power. (Heavy)
4. It has a standard T4 W1 statline. (Light)

From this we can already see that in reality, the assault terminator is basically all over the place.

To give this a simple definition, let’s make this a math thing. Apply a number to each weight value:

Ultralight: 1 Light: 2 Medium: 3 Heavy: 4 Superheavy: 5

With these values in mind, we will take the Assault terminator’s values and find the average.

(5+3+4+3)/4 = 3.75 Since 3.75 is closer to 4 than to 3, it is safe to simply call an assault terminator ‘heavy’. However, by virtue of its role, characteristics and mobility, an assault terminator can never truly qualify for a ‘Superheavy’ role.

Yeah, but Lysander.

Another example, this time using Lysander: he can be defined in four similar points (I’m assuming he’s actually being run with assault terminators)

1. He has a 2+3++ save. (Superheavy)
2. He wants to move very quickly, but can’t. (Medium)
3. He wants to close into assault with hard-hitting power. (Heavy)
4. He has a standard T4 W4 statline with eternal warrior. (Superheavy)

In this case, his values add up to a solid 4.25, meaning he is on the heavier side of heavy; but he still cannot be considered ‘Superheavy’.

Light Infantry, but Static?

Light armour makes for light qualities

A unit like a Guardsman squad with multiple lascannons is a good example of where light armour can become medium or even slightly heavy. Once again, guardsmen are defined in four points

1. They have a 5+ save (Ultralight)
2. They do not intend to move, even if it may be the death of them. (Superheavy)
3. Intending to provide heavy Fire Support. (Heavy)
4. Has T3 W1 statline (Light)

As you can see, the role and mobility of the average heavy weapons guardsman means that he is as varied as an assault terminator. This ultimately gives him an average value of three, moving them from their role as ‘Light infantry’ to “Medium infantry” in the space of their role.

And Veterans?

It is easy to say with their heightened qualities that a veteran squad is intended to be a medium infantry, but is this the case? Usually, Veterans are run fast and far, with either chimeras or Valkyrie/Vendetta gunships to carry them. As a result, their status as ‘Medium infantry’ in the Guardsman army is under threat.

Once again, Veterans are defined by four points:

1. A 4+ save (Light)
2. They tend to attempt to cover a  lot of ground (Light)
3. They can either be used to attack specific targets or to capture objectives (Medium)
4. They have T3 and W1. (Light)

By this very admission, Veterans become a lowly 2.25 – putting them at the high end of light infantry.

Understanding the way ‘weight’ of infantry should be discerned may enable armies to be better critiqued and may help with fire options when it comes time for shooting. Hopefully these descriptions have been fairly clear, but questions are always welcome.

Okay, sure. What about a monster?

Trygons are an excellent example.

Their four points:

1. A 3+ save (Medium)
2. They tend to cover a lot of ground to get into assault (Medium)
3. They are going into assault to cause a lot of damage, dangerous for tanks. (Superheavy)
4. They have T6 and W6 (Superheavy)

Unfortunately for the Trygon, his lack of an invulnerability tends to force him to be slightly weaker; his two medium stats forcing him into the heavy category at 3.75 (actually making him lower than even Lysander.)

Though this makes sense; it takes only 6 lascannon (roughly 14 lascannon shots, guardsmen) wounds to kill him, whereas it takes about 12 lascannon wounds to fell Lysander (28 shots from guardsmen)

Noteworthy:

While I’ve tried to make this as simplistic as possible, there was a little bit of math behind the way things are defined. While Mobility and Role are not strictly defined, Statline and Armour is.

Armour:

Armour has used this system to provide rankings:

6-5+: Ultralight

4+: Light

3+: Medium

2+: Heavy

1+: Superheavy

Modifiers were applied for invulnerable saves

6++: -1 to armour save value

5++: -2

4++: -3

3++: -4

2++: -5

FNP: -1

(Invulnerable saves alone were considered to be one point lower and as armour save, if the model had no armour save.)

Statline

T1-2: Ultralight

T3-4: Light

T5: Medium

T6-8: Heavy

T9-10: Superheavy

T	Level	W
1-2	Ultralight	1	0
3-4	Light	2	1
5	Medium	3	2
6-8	Heavy	4	3
9-10	Superheavy	5-10	4
		Eternal	2

Other Notes:

I've used two images in this, neither of which I own. While I've made my best effort to make them aware/gain permission for their use, I've effectively failed. That said, I'm a bit of a rebel, and I used them anyway.

Obviously, I'm a terrible person.