I think I see your point. I think it lies at the opposite extreme of the spectrum compared to mine (i.e. you really really want to stop any aftereffects); in that, I think it's "cleaner" than other views I've seen posted. However,
a) I still do not agree and
b) I still think it leaves a very large grey area, because you have to rule on what is ongoing damage, and what is a "natural" negative consequence of damage inflicted during the War. For example, I really think that weakening the opponent's body so that it most likely collapses to the ravages of time over the next decade is no different than weakening his laboratory so that it most likely collapses to the ravages of time over the next decade. But, if I understand correctly, you'd rule the first was lawful and the second wasn't (leaving aside the risk of collateral damage).
One last thing. It's not clear to me how you would treat:
a Rego effect that steals some of my opponent's equipment during the war (say a book). Do I have to return it when the war is over? One could argue that my taking it was an "instantaneous" action, but also (by your arguments) that my withholding it from him after the War is over is a continuing deprivation of magical power.
a Rego effect, with momentary duration, that just flings the opponent to some place from which he can't return, and in which he may eventually die e.g. of starvation (say, an oubliette). Do I have to "rescue" the opponent when the war is over, or at least e.g. notify his sodales?
The damage (loss of the book through theft or destruction) occurred during the War - thus it is permissible, and does not need to be compensated for. It falls under the same category of "you chopped my arm off!" While the consequences of the damage continue (ie, you either continue to not have the book, or you don't have your arm), the damage itself was caused during the War - and is thus permissible.
The argument would be "loss" of magical power - but the loss occurred during Wizard's War, and thus is covered by the Code. You don't "continually loose" something once it's been taken from you. Thus, the magus isn't "continually stealing" the book.
Further, once a book becomes the legal property of another magus, they are not obliged to give it back: that's the definition of "legal property", apparently (same rule as for apprentice-snatching). Property is explicitly covered as "a permissible thing to keep" as a consequence of Wizard's War. But regardless - in both circumstances: you are not permitted to chop off your opponent's OTHER arm, or steal the REST of their library, once the War is over.
The "damage" was the teleportation effect. Same as stabbing them with a sword and leaving them to die: you aren't required to do anything about it. But as you imply: if it were an ONGOING Rego effect that (say) kept them from leaving the cauldron of an active volcano, then you'd have to undo the effect.
EDIT - That being said - it's illegal to imprison another magi when you aren't in Wizard's War - so that may fall under a completely different set of rules. If you teleported them to an area you control, you are oblidged to let them out. If you teleported them to (say) the middle of the Sahara, then that's their problem.
So if the oubliette was in your Sanctum, you could do whatever you pleased: Sanctums are permanent Wizard's War locations, basically. But if the oubliette was just in the Covenant (say, in the basement, or something), you'd be obliged to let them out.
I tend to like that you can cast a watching ward that incinerates your opponent 2 months latter when he stops being craven and returns home.
However, I have found a flaw in my original impression. Suppose I declare, let's say 50 wizards wars, one for each political opponent of mine. And then I run to hide in an unassailable place. I have previously collected AC to all these people. Now I put 50 watching wards IN MY TALISMAN. Next time I go to the tribunal arena (or any other gathering where I coincide with one or more of the targeted magi) all my political opponents will be incinerated. Would that be allowed? I guess not.
I am liking the Moon thing: WW last a moon for a reason I suppose (even if it is just coincidence and not the original intent of the authors of the game). That would mean that ongoing effects you created need to stop after that Moon expires. So the summoned pack of wolves needs to be dispelled even if it is year duration and the poison needs to be stopped from continuing action (even if the damage so far does NOT need to be repaired) at your expense. A good reason to use Instant or Moon effects (at most), I guess.
Just my opinion on a few things- using a watching ward or other delay to cause a spell bombardment at the beginning of a war would seem okay, as long as they were cast after the confirmation of the start date was received (don't want to cast that then find out your wizards war was delayed a moon due to slow mail delivery)
a scrying device or spell which lasts beyond the moon might be okay to keep and not use if, for example, you set it aside and turned around and declared another wizard war on the same opponent, taking out the scrying spell/device only when the war was back in effect. Expect someone will have you investigated on that question though...
If the spell takes effect after the war it is no good, if it has effects which endure after the war (loss of a leg, lingering illness, living impairedness) then that is acceptable.
Part of winning a Wizard's War involves dealing with the legal fallout.
Even without a WW, suppose I poison some random lake. If a traveler drinks from the lake and dies, am I a murderer? I didn't do anything to the traveler, nor did I force him to drink. Some legal systems will rule one way, others another, others will look further into circumstances (to whom does the lake belong, is poison always considered evil but if I just stole the guy's food and he starved to death that's just theft not murder, what was the intent, etc), others will take a vote.
Different Tribunals will rule differently, and the magi involved will also matter.
Maybe the best way to win a WW is to declare a March, knowing that you and your buddies will get approval from your Tribunal five years down the road when they meet. None of those pesky WW rules apply, and the target's covenant-mates are fair game if they don't cooperate.
A WW used to be by express agreement by two Magi. Did that change in 5e?
In previous games we've house ruled that the tribunal needs to also approve the war between two Magi, and then designate the period of the fight. As SG my in-game explanation was that the tribunal did not want Magi at war ever but recognized the need, so set their rule to distribute the events of chaotic fighting. His also gives plenty of time for the heads to cool, and also plenty of planning time.
If you have the right reputation and status, I think you could get away with it. After all, the Tribunal can declare the magus renounced after the fact! Ex post facto is not yet standard. (And even today, not all legal systems support that right.)
True. Very much true. Dealing with the aftermath of a March or WW requires the expenditure of political and perhaps other capital. The other nice thing about a March is that a single event can sometimes deal with a few foes.
Too many WWs will also cause problems.
I think that an unpopular magus executing a proper WW against a popular magus will immediately suffer similar problems, as friends and allies of the late, popular magus press charges in Tribunal for various alleged technicalities, and letting the issues come to a vote.
I would expect that the Flambeau, Tytalus and-probably-several of the other houses would have a problem with that. The code says their is no sanction for killing someone in wizards war (though the allies of the slain can declare war on you).
A wizard's war must be declared by 1 side, and formally doesn't begin till the new moon FOLLOWING the next one from the declaration. A redcap must witness the receipt of the declaration (usually the redcap who delivers them). It's completely possible to ignore a declaration in the sense of not giving a damn about it, but not possible to fail to receive one, essentially, if you have a fixed abode.
Illegal because the Beast (which you summoned and ordered) killed him outside the Wizard War period. However, possibly not easy to determine responsibility in this case. For it to matter, somebody who cared enough to bring the case at Tribunal would have to prove (for example, detect via spell traces) that you summoned the Beast. So, the death might easily be mistakenly attributed to "magus killed by horrific, but random, beast attack".
What about the opposite case? The Beast is summoned and ordered prior to the Wizard War, but does not actually attack or kill the target until during the Wizard War period. For me, this would be entirely legitimate, as the attack happened during the Wizard War period. However, according to my understanding of your interpretation, it seems that this would be illegal, because the spell was cast before the War was declared. Of course, it could still be difficult in practice to prove when and by whom the Beast was actually summoned/ordered.
If we go for a strict approach and say that only spells cast during the WW can be used, you would be unable to use an Aegis to protect yourself during the WW unless it was cast when the WW was beginning. Same for watching wards placed in your covenant placed there to protect against interlopers, like alarm spells.
So, I think that the summoned creature is OK if it attacks during the WW period. It will need to be restrained by you once the war ends, though. Unless you can prove that you only set it free but that it was the creature's work and will that caused the death after the WW ended.
With regards to the throwing someone to somewhere they have trouble getting back from via a rego spell... well, most magi would look upon it as "He's not a very good magus if he can't get back from that..."