I have three ideas to deal with lucky strikes. The Antiluck Charms I described twice already, I think? The Pillar of Unmagic(intended to be a national effort and might take time and/or revision to attune it to "the thing that is making their artillery accurate") and finally:
Living Crystal Charms
While referred to, and appearing as, charms, this is not actually derived from antimagic charms.
By imbuing the "spark of life" found in our conjured fire-wasps instead into a crystal we have granted the crystal the ability to react to stimuli.
By combining it with a gem(A ruby, ideally, over the heart, though other red gems also work if you don't mind a risk of cracking under stress.), mages are able to recharge it, and imbue it with reserve energy.
By imbuing it with a variant of channelled fog, it can continuously resummon an extremely fine, effectively invisible, cloud of minute crystal particles. These particles only last a moment before fading and being resummoned, as any more would have an immense magic cost, but it can transmit its "will" through this cloud and sense any movement or magic within the cloud.
Being crystalline in nature, the charm's "life" is only partially physical, as it lacks the moving parts required for conventional life, it needed to be a living entity that exists partially as a "pure" expression of magic. This grants it some measure of magical awareness that can be matched only by the most sophisticated of our gem arrays back at the lab, and can thus react to them much faster than anything we could hope to match using current techniques.
Finally, the crystal charm effectively exists in two forms. The first form, is an unassuming necklace with a crystal growth around a red gem. The second form is that of a crystal shell, of a thinckness that defaults to five centimetres, that completely coats the wearer while perfectly contouring to their body, actually suspending their clothing and equipment within its structure to completely encase the subject. We had some, unfortunate incidents... with the prototype, but have included strict protocols to prevent it lasting more than 20 seconds in this latter form.
The basic functionality is to encase the wearer in a nearly invulnerable shell of crystal as soon as imminent injury to the wearer is detected. We have done what we could to keep our first experience in living crystals from being too eagre or shy in this duty, but... well, we are hopeful that it will properly defend against anything lethal or crippling and disable itself promptly to conserve power when the threat has passed.
The advanced functionality is to have the charm respond dynamically to threats. A single centimetre of crystal shell is far more than enough to deflect any arrow, but we worry that the enemy could expand their project and something even greater than the absurd five-centimetres projected for the production model would stop, and we have not tested it against a point-blank fireball or cannon round... So we hope that it will use its "mind" to determine what is required and protect accordingly, but should stick to the default if it doesn't know.
The metamagic effect is that it is a wilful being with a significant awareness of magic and a reserve of magical power, it can "fight" magical attacks to its own being, and in doing so, defeat the enemy effects to disable its magic. We have tried training them against antimagic charms, which obviously do not dispel the crystal construct but have been noted to often "blind" them and inhibit their transition into a shell. We don't know how similar this is to enemy antimagic, but we hop to question some of these magical beings after they have had first-hand experience of the enemy's effect, assuming that they survive or can be regenerated from the original gem after being dissipated... This is all conjecture, but the "living spell" project has shown great promise as a theory of countering the enemy antispellcraft.
The projected performance is to persist 20 seconds of shell form or two hours in charm form. Or 10 seconds in shell form AND 1 hour in charm form. Or some other combination following that ratio. On a wizard the power can be restored with focus and will, allowing it to remain indefinitely so long as the wizard takes regular breaks from their other duties...
And thus we have something that will make our wizards extremely uncomfortable in order to make them continue living. It isn't anchored though, and crystals are light, so it is less likely to break than a steel fortress of the same thickness, but a particularly forceful blow could injure or kill them by accelerating them quickly... Also, lightning is fast, so it may not stop lightning until it learns what the buildup of charge means, so people should be encouraged to loot these from the dead, as they can learn and the same thing ought not to work "lightning doesn't strike twice"...
...
Rod to God literally gets my vote.