Ruleshammer: March 12th, 2021 – Auras, Fast Dice, and Dense Cover

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This week I won’t be addressing specific questions but instead I’m going to take a bit of a delve into three areas of the rules that have come up a lot in relation to a lot of the game’s current issues.

Determining if an Ability is an Aura

So what’s an aura? This one is a bit less obvious than you might think, even in 9th edition books. The first thing to note is that the definition of an aura in the Core Rules is not “abilities that include the (Aura) tag.” If this were the definition of an aura, then none of the 8th edition rulebooks would have auras in them, and they’d need individual errata updates to add the (Aura) tag – which hasn’t happened – and abilities like Contagions wouldn’t need additional text clarifying that they aren’t auras, which also wasn’t the case. Let’s look at the definition of an Aura in 9th edition:

Aura Abilities
Some abilities affect models or units in a given range – these are aura abilities. A model with an aura ability is always within range of its effect. The effects of multiple, identically named aura abilities are not cumulative (i.e. if a unit is within range of two models with the same aura ability, that aura ability only applies to the unit once). [Core Rules PDF Pg7]

This doesn’t mention abilities tagged as Auras – that’s a convenience being added to 9th edition books, but some abilities have already been missed by this despite being auras. Do I wish this explanation was longer? Yes. Do I wish there were some examples? Absolutely. Is this mostly sufficient for us to determine what rules are auras from those that aren’t? Yes.

So really it’s just the first sentence that actually explains what an aura is. This broader definition of Auras has several implications, such as the aforementioned need to specify that Death Guard contagions are not auras:

Note, that while similar in many regards to Aura abilities, Contagion abilities are not affected by abilities that affect Aura abilities, and vice-versa.

Alright, let’s go through some examples.


From 9th Edition Books

Despite many Aura abilities in 9th edition having the [Aura] tag, there are some that did not receive the tag, but are still Aura abilities.

Lychguard. Credit: Wings

“Bodyguard” Abilities: Is an Aura

Bodyguard abilities went through a lot of changes throughout 8th and are being replaced by an entirely new mechanic in 9th edition rulebooks. I’ve gone over how it works a few times but addressing specifically today if this ability is an aura, the answer is: Yes.

Space Marines – Bodyguard: While a friendly <CHAPTER> CHARACTER unit that has a Wounds characteristic of 9 or less is within 3″ of this unit, enemy models cannot target that CHARACTER unit with ranged attacks.

Necrons – Guardian Protocols (Aura): While a friendly <DYNASTY> INFANTRY NOBLE or DYNASTIC AGENT INFANTRY NOBLE unit is within 3” of this unit, enemy units cannot target that unit with ranged weapons.

Death GuardBodyguard (Aura): While a friendly <CHAPTER> CHARACTER unit that has a Wounds characteristic of 9 or less is within 3″ of this unit, enemy models cannot target that CHARACTER unit with ranged attacks.

The keen-eyed of you may have noticed that the Space Marine codex is missing the tag here – however that does not change that the ability is an Aura. Going back to the definition the effect they have on a character unit in range is that they prevent them from being targeted. The (Aura) tag is a helpful reminder, but not the defining trait.

Obeisance Generators: Not an Aura

Some very aura-like abilities are in fact, not auras. This rule is one of the more subtle non-auras released so far:

Obeisance Generators: At the start of the Fight phase, if there any enemy units within Engagement Range of Szarekh, then until the end of the phase, those units cannot fight until after all other eligible units from your army have done so.

At face value it has some of the key features of an aura – it has a range, it’s an ability. Where it differs though is that it doesn’t ONLY affect units in range, they continue to be affected until the end of the phase even if during that phase they are no longer “in range”. This persistent effect is why it is not an aura, the Silent King could die or move away from some units (if there was a unit closer) via Pile in or Consolidate and the units affected by this ability would continue to feel its effects until the end of the phase.

White Scars Infiltrators Credit: Alfredo Ramirez

White Scars Infiltrators Credit: Alfredo Ramirez

Some abilities affect units outside a specific range rather than inside a specific range. These are also not auras.

Omni Scramblers: Not an Aura

Omni Scramblers: Enemy units that are set up on the battlefield as reinforcements cannot be set up within 12″ of this unit.

This is perhaps one of the abilities that is most frequently mistaken for an aura. The key distinguishing feature here is that if a unit cannot be set up within 12”, then it’s being affected by this ability when it is outside 12”. This does not meet the aura definition of abilities that affect units “in a range”. Omni Scramblers affect every unit not on the board yet; that’s not units in a specified range.

Raven Guard Shadow Masters: Not an Aura

Shadow masters is not an aura for the exact same reasons as Omni Scramblers – it affects all units outside a range. However I felt it worth mentioning here because of how aura-extending abilities would affect it if they applied. Increasing the range of Omni Scramblers – if it were allowed – would provide a large benefit, forcing the opponent to deploy even further away. In a more humorous turn, increasing the range of the Shadow Masters ability would instead be a significant decrease in benefits:

Shadow Masters: Each time a ranged attack is made against a unit with this tactic, if the attacker is more than 18″ away, then the unit with this tactic is treated as having the benefits of light cover against that attack.
Each time a ranged attack is made against an INFANTRY unit with this tactic that is entirely on or within a terrain feature, if the attacker is more than 12″ away, then the unit with this tactic is treated as having the benefits of dense cover against that attack.

If this ability was an aura, then increasing the ranges mentioned by say, 6” would mean Raven Guard units only got their first effect against enemy units 24” away rather than 18”, making the ability worse – the enemy wouldn’t need to get as close to turn off the benefits of this ability.


From 8th Edition Books

Tau Pathfinders

Tau Pathfinders. Credit: Jack Hunter

For the Greater Good: Is an Aura

Each time an enemy unit declares a charge against this unit, this unit can fire Overwatch before the charge roll is made.
While a friendly unit with this ability is within 6″ of this unit, each time an enemy unit declares a charge against this unit, that friendly unit can fire Overwatch before the charge roll is made. If it does so, until the end of the phase, that friendly unit cannot fire Overwatch again.

This is a weird one, but it’s the second part of this ability is the section that meets the definition of an Aura. It’s essentially a single ability with two effects. What I haven’t been able to find in the current rules is any example of an ability combines an aura and a non-aura affect into the same rule. However, as any part of this ability meets the definition it should be treated as an aura. This has knock-on effects, as abilities that prevent units from using auras abilities would then arguably disable both parts, despite the first part not being an aura effect. Yeah, it’s a bit of a mess.

Opinion: As a Tau player myself I would still treat the whole thing as an aura and just accept that if it’s disabled then my units also lose the ability to fire overwatch without the overwatch stratagem.

Waaagh!: Not an Aura

Friendly <CLAN> INFANTRY units within 6″ of this model at the start of the Charge phase can charge even if they Advanced this turn.

This is a nice, simple, clear one – affects units in a range, giving us a nice, straightforward aura. Sorry. On a second read this is in fact not an aura. The effect is actually persistent, even if the unit with Waaagh moves away it continues to affect the units that were within 6″ at the start of the charge phase. Trust Orks to have a sneaky one.

Alpha Legion: Hidden in Plain Sight: Not an Aura

Hidden in Plain Sight: Your opponent must subtract 1 from hit rolls that target units with this trait if they are more than 12″ away.

I’ve included this one because it is essentially the same as part of the Raven Guard chapter tactic, but from a 8th edition codex. As with the Raven Guard ability, it affects all models outside its range (12”) rather than units in its range, which means it is not an aura.


Dark Angels Blade Guard Veterans and Ancient

Dark Angels Blade Guard Veterans and Ancient. Credit: Greg Chiasson

Auras in 9th Edition books that are missing the (Aura) tag (that I’m aware of)

This list is not exhaustive – Bodyguard in Codex: Space Marines is the prime example of this but there are others. If you think you’ve found another example in a 9th edition book but you’re not sure, please feel free to submit it to the Ruleshammer form.

Dark Angels

Feast of Malediction: While a friendly DARK ANGELS CORE unit is within 6″ of this PRIEST, add 1 to the Attacks characteristic of models in that unit.

This is a litany that a DA Chaplain can gain via the Cup of Retribution relic, and it meets all the criteria of an Aura. Units in a range are affected.

Reliquary of the Repentant: Ravenwing Biker model only. While an enemy unit is within 3” of the bearer, each time an invulnerable save is made for a model in that unit that has an invulnerable save of 4+ or better, the saving throw is only successful on an unmodified roll of 5+.

This wording on this ability changed between the Dark Angels Index and the Codex Supplement; the original wording had the (Aura) tag. Despite losing that tag, the ability still meets all the requirements for being an Aura, and as such, is an Aura.


Troubles with Dense Cover

Rules-wise, Dense Cover is weird. I think most players are fully aware of that. The second thing of note is that it’s also a slow rolling nightmare some of the time. The reason for this is because the benefits of Dense Cover are a “per attack” check.

If this terrain feature is at least 3″ in height, then subtract 1 from the hit roll when resolving an attack with a ranged weapon unless you can draw straight lines, 1mm in thickness, to every part of at least one model’s base [or hull] in the target unit from a single point on the attacking model’s base [or hull] without any of those lines passing over or through any part of any terrain feature with this trait.

The issue here is that this can change per model during shooting on a per-Attack basis:

Note that this is a rather extreme example. Most of the time you’ll likely be able to group targets up so you can speed this up and still play it accurately. If the Fire Warriors unit had 3 models visible to those two Necron Warriors then you could make 3 attacks at once, for instance.


Look at those sexy dice. Where can *I* get some? Editor’s Note: You cannot, in fact, “get some”

Fast Rolling Dice Rules – things to remember

First of all the strangest thing about this, is that the Fast Rolling Hint/Tip is ONLY in the Big Rule book. It’s not included in the Core Rules PDF or GT2020’s rules section.

Fast Rolling Dice
The rules for making attacks (pg220) have been written assuming you will resolve them one at a time. However, it is possible to speed up your battlers by rolling the dice for similar attacks together. In order to make several attacks at once, all of the attacks must have the same Ballistic Skill (if a shooting attack) or the same Weapon Skill (if a close combat attack). They must also have the same Strength and Armour Penetration characteristics, they must inflict the same damage, they must be affected by the same abilities, and they must be directed at the same unit. If this is the case, make all of the hit rolls at the same time, then all the wound rolls. Your opponent can then allocate the attack one at a time, making saving throws and suffering damage each time as appropriate. Remember, if the target unit has a model that has already lost any wounds or already had an attack allocated to it this phase, they must allocate further attacks to that model until either is is destroyed, or all the attacks have been saved or resolved. [BRB Only (for some fucking reason) Page 221]

Things to unpack from this:

All the attacks must have the same S, AP, and Damage

D3 and D6 damage weapons do not have the same damage but you can still fast roll and account for this later. This has been well understood practice for a while; just slow roll the damage at the very end if you’re attacking a unit of multi-wound models. This allows you know the order the damage occurs in, 2D3 might kill a 2W model and then wound another, or just kill a single model depending on if the results are 3 then 1, or 1 then 3. Standard stuff!

All the attacks must be affected by the same abilities

This one is tricky. It comes down to when a model is “affected” by an ability. I know some players will disagree but this is the neatest interpretation I’ve got to help identify when fast rolling might lead to a different outcome to slow rolling. Essentially II would argue that if a unit has abilities that trigger on a 6+ to hit or wound for instance, then you don’t know which models are “affected by the same abilities”. You knew which models might be affected, but as models that didn’t roll a 6+ are not affected by these rules I think this is a pretty fair read. What does this mean though? It really only comes into play for overheating weapons that might kill the model that has them, Plasma Interceptors for instance. There are others though which have different levels of impact on the attack sequence

Weapon abilities that cause a mortal wound ability shift those mortals to the end of the attacks for the whole unit so they don’t actually make any difference, you resolve the attack as normal and then resolve the mortal wounds afterwards.

Multiple attacks that inflict mortal wounds
Some attacks can inflict mortal wounds either instead of, or in addition to, the normal damage. If, when a unit is selected to shoot or fight, more than one of its attacks that target an enemy unit have such a rule, all the normal damage inflicted by the attacking unit’s attacks are resolved against that target before any of the mortal wounds are inflicted on it.

Abilities that increase the AP of a weapon a particular roll arguably also don’t meet the “same AP requirement” of fast rolling. In practice the wound allocation rules in 9th limit the impact of these effects as players have to continue allocating wounds to models once allocated once in the phase. This limits how useful knowing beforehand how many of the incoming attacks will be of a higher AP.

Abilities that cause additional attacks or additional hits. Honestly I don’t think these make any difference at all that I can discern assuming the attack meets all the other requirements of Fast Rolling.

One More Thing: You can’t technically fast roll saves.

This is really just because of how Damage allocation and arguably how AP and cover work in 9th. You can usually group saves fairly simply but the key thing here is that the rule firmly establishes that saves are one at a time, so the result must not be altered from what it might have been if you rolled those same results one at a time.

We’re not saying you should never fast roll saves in groups when it makes sense, just that this isn’t what the rules technically have you do and so it’s worth being cautious and noting when it makes a difference in game results.


Have any questions or feedback? Got a rules question you want answered? Drop us a note in the comments below, ask a question in our Ruleshammer form, or head over to r/ruleshammer to discuss.


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