The other time is when the result of the wound roll has some special ability which might impact the odds of a successful armour save... I dont think there is anything in the current Necro ruleset, but I am certain there are other GW products where an additional armour modifier has resulted from a particular 'wound' roll.
There is one here, in the Shooting skills, marksman or something. Roll a 6 on To Wound, and voilà, no armour saves allowed.
That doesn't really help with the whole problem, GeeDubs just can't make the right system.
All there is to do is just create Saves section of the rules
like (example)
There are multiple ways of avoiding harm, called saves. A save is performed by rolling D6
Armour saves: The most basic saves, provided by Armour or (un)natural protection. They can be modified or even negated.
Invulnerable saves: Advanced tech or otherwordly influence allowes you to avoid modification. These saves are taken instead of Armour saves, and can never be modified.
Ward saves: provided by skills, precognition or power fields, they allow one to avoid getting hit whatsoever, and are to be used just after the opponent has landed a successful Hit. They cannot be modified.
But the main initial idea behind SAVING is that it's supposed to be the last roll, when you save yourself. Saving before the whose sequence does sometimes feel anti-climactic...
especially when you're a 485 point beast that just rolled three 5+ fields in a row with NOPE NOPE NOPE sound. It sounds fun but your opponent just wants to throw you and the dice out of the window.
Good point! Actually, there is one Trait that does something like this: Seismic.
Assuming Field armour gives you a 'save roll' (as strongly implied by the wording of the Power trait and the 'Resolve hit' rules) then they can't do anything before the Wound roll is made, because (in the case of Seismic attacks) you need the result of the Wound roll to know whether a save roll is even allowed.
Funny enough, it is not called a Saving roll in the wording, just as it's not called save in skills or familiar powers.
It's called a save in the paragraph at the beginning of fields section, but not in the rules for fields themselves.
And if we don't consider them saves, and take them against Hits as per RAW, Marksman and Seismic effects trigger and still have effect, denying the use of armour roll on step 6.
Though I am sure GeeDubs will (as always) do the opposite of what they've written and act as if it was the intention
I shall advocate for RAW, especially considering this RAW is more logical than not.