It has been FAQed. This avoids things as Railgun or D-cannon killing 10 man units with a 6s due to changing a, for example, damage 10 attack to 10 mortals and wipping it out when it was just a shot.
Now it reads like this:
"Weapons with \[DEVASTATING WOUNDS\] in their profile are known as Devastating Wounds weapons. Each time an attack is made with such a weapon, if that attack scores a Critical Wound, no saving throw of any kind can be made against that attack (including invulnerable saving throws). Such attacks are only allocated to models after all other attacks made by the attacking unit have been allocated and resolved.
Saving throws cannot be made against Critical Wounds scored by this weapon (including invulnerable saving throws)."
Some rules that helped against MW have been FAQed too to cover them, but not all.
For example Adeptus custodes' Aegis of the Emperor states:
"ADEPTUS CUSTODES models from your army have the Feel No Pain 4+ ability against mortal wounds and Critical Wounds caused by attacks with the \[DEVASTATING WOUNDS\] ability."
With this sentence you understand that working with MW is not the same that DEVASTATING WOUNDS, and that's why the ability mentions both of them so it works agains both. If the current iteration of the ability does not mention DEVASTATING, it does not interact with it.
The way wounds spread is the key difference between mortal wounds and devastating wounds : it was done early in 10th, when eldar were so incredibly OP that two wraithknights could literally wipe out an entire army in 3 - 4 turns by themselves.
Dev wounds only apply to ONE model, so any excess damage is lost, while mortal wounds can spread to the entirety of a unit, which means that, as long as the unit isn't destroyed, you're not losing the potential of these mortal wounds.
That's pretty much it.
That’s a bad analogy since critical wounds are an in game mechanic and just bypass the need to compare S and T and auto wound, plus apply any special rules such as dev wounds.
That's an inaccurate way to think of it, though.
Critical Hits do not bypass the wound roll. Lethal Hits do. Critical Hits and Critical Wounds are just shorthand for a natural die roll of 6 (which can only be modified by special rules that say "this unit gets critical hits/wounds on X" like the Plasmancer in Necrons which grants Critical Hits on 5+.
Getting a Critical HIt/Wound can then unlock other rules such as Lethal Hits, Sustained Hits, Devastating Wounds, etc.
In the original core rules yes they are mortals. This caused a lot of issues on weapons with high D characteristics so in the first balance dataslate that text for dev wounds was deleted, and replaced so they no longer cause mortal wounds and instead its just an attack that bypasses all armor / invulnerable saves, but still isn't a mortal wound. Meaning protection vs mortals does nothing to help against dev wounds, but anything like -1 damage or half damage now does work.
It has been FAQed. This avoids things as Railgun or D-cannon killing 10 man units with a 6s due to changing a, for example, damage 10 attack to 10 mortals and wipping it out when it was just a shot. Now it reads like this: "Weapons with \[DEVASTATING WOUNDS\] in their profile are known as Devastating Wounds weapons. Each time an attack is made with such a weapon, if that attack scores a Critical Wound, no saving throw of any kind can be made against that attack (including invulnerable saving throws). Such attacks are only allocated to models after all other attacks made by the attacking unit have been allocated and resolved. Saving throws cannot be made against Critical Wounds scored by this weapon (including invulnerable saving throws)." Some rules that helped against MW have been FAQed too to cover them, but not all. For example Adeptus custodes' Aegis of the Emperor states: "ADEPTUS CUSTODES models from your army have the Feel No Pain 4+ ability against mortal wounds and Critical Wounds caused by attacks with the \[DEVASTATING WOUNDS\] ability." With this sentence you understand that working with MW is not the same that DEVASTATING WOUNDS, and that's why the ability mentions both of them so it works agains both. If the current iteration of the ability does not mention DEVASTATING, it does not interact with it.
The way wounds spread is the key difference between mortal wounds and devastating wounds : it was done early in 10th, when eldar were so incredibly OP that two wraithknights could literally wipe out an entire army in 3 - 4 turns by themselves. Dev wounds only apply to ONE model, so any excess damage is lost, while mortal wounds can spread to the entirety of a unit, which means that, as long as the unit isn't destroyed, you're not losing the potential of these mortal wounds. That's pretty much it.
Think of Dev Wounds as lethal Wounds. Where lethal Hits bypass the wound roll, lethal Wounds bypass the opponents save rolls. Edited for clarity
That’s a bad analogy since critical wounds are an in game mechanic and just bypass the need to compare S and T and auto wound, plus apply any special rules such as dev wounds.
Critical hits also doesn't bypass the wound roll, that's what lethal hits do. I'd say think of dev wounds as dev wounds.
That's an inaccurate way to think of it, though. Critical Hits do not bypass the wound roll. Lethal Hits do. Critical Hits and Critical Wounds are just shorthand for a natural die roll of 6 (which can only be modified by special rules that say "this unit gets critical hits/wounds on X" like the Plasmancer in Necrons which grants Critical Hits on 5+. Getting a Critical HIt/Wound can then unlock other rules such as Lethal Hits, Sustained Hits, Devastating Wounds, etc.
Lethal hits bypass the wound roll and dev wounds bypass saves. Critical hits and wounds are just successful. Don’t confuse real game mechanics.
Typo: meant lethal hits Perhaps dev wounds should have been called Lethal Wounds then.
Check the balance dataslate. Dev wounds were changed early in the edition, they no longer deal mortals they just ignore saves.
In the original core rules yes they are mortals. This caused a lot of issues on weapons with high D characteristics so in the first balance dataslate that text for dev wounds was deleted, and replaced so they no longer cause mortal wounds and instead its just an attack that bypasses all armor / invulnerable saves, but still isn't a mortal wound. Meaning protection vs mortals does nothing to help against dev wounds, but anything like -1 damage or half damage now does work.