Back in the old days when Ars Magica v3 was new I think the rules for Wizard’s Wars stipulated that both parties had to agree to the conflict. Either it was in the book, or the guys I played with made that house rule. Sure, a big nasty wizard could threaten another, intimidate, or whatever, but could not just declare a war and start killing somebody else. In v5 one wizard can declare a war on another, and it just starts automatically a month or so later. No acceptance, no agreement. Fight or flee.
In the flavour and fluff a WW is meant to be a way to resolve disputes and is also meant to be a last resort. It is also meant to be frowned upon by the Order of Hermes for a wizard to start waring with many people, or the same people repeatedly.
We also have a setting in ArM v5 which presents a more orderly, bureaucratic, and safer Order of Hermes than older editions. The Order accepts and has laws that allow bullying and murder in the oaths. I find that combination of views an incongruity, and it bugs me. How could it possibly be safer? Younger wizards are at a huge disadvantage, and specialists in certain type of fighting will be hard to stop by non-specialists.
There is also an implication that the result of a Wizard’s War isn’t lethal. This doesn’t make any sense either. As the defender in a war which wasn’t desired, if you survive, you better power-up and kill that attacker. And make sure you wipe him out. If the attacker misses the first time, you might have some breathing space, but eventually it will happen again. Entering a potentially lethal conflict isn’t something anyone does lightly, and the instigator of a war probably knows what they are getting into. The Order in the present cannon offers you no protection except somebody waggling their finger at your killer afterward. I do not understand the idea of surviving a life threatening (magical) attack and then not expecting it to happen again.
The current lore places the typical starting scenarios so close to immediately lethal that all the exceptions are feint edge cases. Huh? Hardly safer.
In my games the wars have to be agreed and sanctioned by the Order. That gives the tribunal the overview of the activity, and also control of harassing behaviour before wizards start dying. It’s not cannon, but it makes far more sense in the setting. The Order of Hermes didn’t grow to it’s size by wizards casually murdering each other, so any type of one-sided sanctioned murder is silly.