Alternative Rules for Vehicles and Things That Interact With Them

Jan 12, 2021
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Heyo, ChapterAquila92 here!

I've probably been giving this far too much thought since, as much as I'd like to keep up with the current edition of 40k, I'm still far more fond of 7th Edition and earlier for the rules this homebrew is based off of. With that said, I just want to write it down to put it out of my mind for the time being.

As a word of note, I will primarily be writing this for the benefit of players who have never played 40k in any edition earlier than 8th, so much of what I'm about to say will be largely redundant for grognards like myself who remember the older editions.

In any case, let's cut to the meat of the topic: vehicles. In my opinion, they've kind of fallen by the wayside since being shunted to the universal datasheet template in 8th Edition, even after a pretty hefty update before the start of 9th that restored some of their capabilities as viable units. In conjunction with a wounding system that enables any weapon to wound any target on a 6 at bare minimum, vehicles lost a lot of the durability they were known for (GW, in their infinite wisdom as of 8th Edition, decided to cap toughness values to a 1-10 scale while allowing the strength of certain weapons to reach upwards of Strength 16). This has largely resulted in many tanks, some of which once being impervious to all but high-strength dedicated anti-tank weapons (in both lore and older editions), now liable to being plinked to death by mid-strength multishot D2 weapons of middling AP like the humble heavy bolter.

A quintessential example of this would be the Land Rider, which due to how the Armour Value system worked back in 7th and earlier could only be taken down conventionally by weapons of at least Strength 8, barring any special rules. Since 8th Edition, Land Raiders have been assigned Toughness 8, 16 wounds, and a 2+ armour save. This profile certainly looks impressive on paper (and definitely better than most other tanks available in the game), but once the new wounding system is applied, Toughness 8 is currently much more susceptible to being wounded by weapons of at least Strength 5 (I'm discounting weaker weapons here, since most can't exceed a 1/18 chance of successfully inflicting damage to such a target per attack. For comparison, a heavy bolter has a 1/9 chance per attack of inflicting damage against this profile).

To this end, I've decided to dive a little into the abstract of what the Toughness characteristic is supposed to represent in the current edition with respect to vehicles, how it compares to the AV system in previous editions, and attempt to come up with a satisfactory compromise between them that myself and others may find useful as a house rule.

As a general abstract for game purposes, Toughness is a measure of a unit's ability to resist damage in some way, in contrast to Wounds taking damage and Armour Saves preventing damage. This may be the short and sweet of it, but how a unit arrives at that value in-game depends entirely on its nature. Biological units derive their Toughness from their body structure, robotic units derive theirs additionally from the materials used in their construction, and daemons derive theirs from Warp shenanigans. Vehicles however are hollow metal boxes for the most part, meaning that even if a shot were to penetrate the hull, there's no real guarantee that it will actually cause sufficient damage within to cripple the vehicle apart from directly hitting a vital internal system (crew members included) or being the delivery mechanism for something else. As such, it can be reasoned that a Toughness characteristic of a vehicle in 40k is or ought to be based on the abstract of this difficulty.

In many ways, this was already implemented in the old AV system, whereby success in penetrating a vehicle's hull (and thus being able to cause damage) meant overcoming a vehicle's front, side or rear Armour Value (each of which typically ranging between 10 and 14) in what can be considered the equivalent of a wound roll. Back then, the penetration roll typically consisted of rolling a d6, adding the weapon's strength to the result, and comparing it to the Armour Value being tested against. A result equal to the AV (a glancing hit) was able to do a point of structural damage, while a result greater than the AV (a penetrating hit) was potentially catastrophic for the target in question in addition to that structural point of damage. Coming back to the Land Raider example from earlier, a conventional Strength 8 weapon could only inflict glancing hits on the roll of a 6 (incidentally, Land Raiders had AV 14 in all directions) before special rules like Armourbane (additional 1d6 for penetration), Melta (Armourbane at half range), Rending (additional d3 on an initial roll of a 6), or Haywire (additional 4+ chance to penetrate).

Understanding how weapons interact with vehicles here is important to keep in mind moving forward, since we can't really have a discussion about changing the former without discussing the impacts it will have on the latter and vice versa. This will be a topic we'll be returning to as a result.

Short of simply deciding to play 7th Edition or Horus Heresy, my solution for the matter of vehicular Toughness is a bit of a mathematical one. From how the current wounding system works and how the old AV system used to work, we can presume the following:

1. The minimum Strength capable of glancing a given AV must be equal to 6 less than that AV;
2. Any Strength value less than the minimum Strength ought to be less than half of the vehicle's projected Toughness value; and
3. Accounting for an unmodified Armour Save, the minimum Strength ought to be able to wound the vehicle on a 5+ for comparable probability of damaging it.

AV 10 (Min S 4) -> ~T 7
AV 11 (Min S 5) -> ~T 9
AV 12 (Min S 6) -> ~T 11
AV 13 (Min S 7) -> ~T 13
AV 14 (Min S 8) -> ~T 15

As demonstrated, this roughly translates into a metric where every increase in AV starting at 10 corresponds with two increases in Toughness starting at 7.

With that said, unlike the Land Raider, most vehicles in 7th Edition do not have the same AV all around. For instance, Leman Russ tanks in 7th have a 14F/13S/10R AV profile instead, while the Baneblade has a 14F/13S/12R profile. Again, the solution is pretty mathematical. I have opted to use the overall average (counting the side profile twice for an even division of 4) multiplied by 2, followed by subtracting 13 from the result and rounding down to the nearest whole number:

Toughness = (Average AV x 2) - 13

This would give the Land Raider T15, Leman Russ tanks T12, and the Baneblade T13. Rinse and repeat for the nearly 200 in-game vehicles, be it by hand or Excel spreadsheet, substituting the underlined variable names for cell references as needed:

=ROUNDDOWN(2*((FRONT+SIDE*2+REAR)/4)-IF(OPENTOP="Yes",13.5,13))

OPENTOP in this case is a reference to the old Open-Topped special rule, which in this instance represents the slightly more exposed nature of an open-topped vehicle's vital systems. Long story short, if a vehicle's operators are usually exposed and not wearing power armour, it's an open-topped vehicle.

As it so happens, this conveniently lines up with many light vehicles - IG Sentinels especially - being pretty faithfully depicted in-game as is with little to no need to adjust their Toughness characteristic.

Of course, since there's been many vehicles that have come out since 8th Edition and thus don't have AV profiles from earlier editions (i.e. every Primaris vehicle), the best I can recommend is to look at the trends involving other vehicles with similar characteristics and use your best judgment when applying changes.

As stated previously, we can't discuss changes to vehicles without addressing the things most affected by those changes. In this case, anti-armour weaponry. I've mentioned it elsewhere, but I don't fully agree with GW's penchant for bonus damage being the means by which such weapons "defeat armour" over the past two editions. What is needed however is an improved ability to wound such high-Toughness targets with an anti-armour weapon, and the easiest way to do that in 9th at the moment (at least, without resorting to Mortal Wound spam) is to simply grant a +1 to wound units with the VEHICLE keyword. If you so wanted to, you could apply that to any and all weapons that used to have the special rules mentioned earlier for the benefit of penetrating armour.

Any thoughts, queries, concerns about how this might play out?
 
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Jan 12, 2021
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Another solution that has recently crossed my mind, in part thanks to some of the recent leaks in the new Tau Codex for 9th Edition, is for vehicles to impose a penalty to wound if the attacking weapon falls below a certain Strength threshold.

As before, extrapolating from how vehicle AVs work and barring the inclusion of Armour Saves, we get the following distribution of what we can expect for vehicles, assuming we're aiming for the 4+ sweet spot to glance:

AV 10 (6+ @ S4, 4+ @ S6) -> T 6
AV 11 (6+ @ S5, 4+ @ S7) -> T 7
AV 12 (6+ @ S6, 4+ @ S8) -> T 8
AV 13 (6+ @ S7, 4+ @ S9) -> T 9
AV 14 (6+ @ S8, 4+ @ S10) -> T 10

I presume that this is what GW was originally going for, since once again we see T6 and T7 faithfully representing light vehicles without issue, and now with T8 being indicative of most of the more armoured vehicles present in current edition 40k by comparison. In many respects, this solution could easily present the least amount of disruption in the current game.

In effect, inbound attacks at Strength values equal to or less than the value required for that natural 6 to glance would be subject to a -1 penalty to wound:

AV 10 (T6) -> -1 to Wound if =/< S4
AV 11 (T7) -> -1 to Wound if =/< S5
AV 12 (T8) -> -1 to Wound if =/< S6
AV 13 (T9) -> -1 to Wound if =/< S7
AV 14 (T10) -> -1 to Wound if =/< S8

Once again, dedicated anti-armour weapons ought to be able to overcome this penalty, and like in the previous possible solution could simply benefit from having +1 to wound units with the VEHICLE keyword.