u/runnerblank

I wonder what the restrictions and customs exist for Formal Challenges?

Obviously from the legendary thrashing of the Crown Prince by Lorest vi Everard any combat magic can be used in the challenge. And the Crown Prince issued the challenge.

A martial culture like Rellas would have limits on who could challenge who and customs to keep bloodshed to a minimum. Rellas needs their knights for the battle field so duels to first blood might be popular especially with the lower ranks of the knights. Those below the rank of knight would likely be beneath the notice of those knighted or of noble rank.

Now someone like the Butcher would have made a great professional duelist. Admittedly the combat Great Families wouldn't need one. Still it would basically be murder for someone like the Butcher to go up against anyone short of a blademaster or someone with equal combat magic like Solentine Dagarra and the Demarr family. And the non combat Great Families would likely have the best champions they can afford to fight for them.

I expect that refusing to duel someone with obvious combat magic would lead to only a little lost of face and professional duelist are rare or non existent.

I'm looking forward to seeing how Team Andrews world builds this.

We know from a Book 2 snippet, Maggie will be in armor, on a horse, in a battle dodging giant boulders.
From the Tent Book 2 snippet, we know she is on campaign with the Duke and is talking to Wynand Bors, the Commander of the Conqueror Knights, and his wife.

Why?

She is basically a non combatant with knowledge that no one else has. We know that Knights spend five or six years as squires starting at age 12 or so and likely start riding and weapons training years before that.

It is pretty clear that she is engaged to the Duke at that point. Ramond vi Everard is smart enough to never tell her "Over my dead body", but there would have to be a very GOOD reason that he or her favorite cousin and the rest of the family would allow someone so untrained on a War campaign.

So why is she there and is even being taken serious by the Bors?

Besides being Undying and so far being able to speak and read any language...

She was able to free Lute from Silveren's Exultant Call, a rare and powerful Savaric hereditary magic with potent mind manipulation, unremembered stealth, and dangerous monster control.

Silveren even maneuvered Clover to the edge of the roof where if she was freed from his Call, she would likely fall to her death.

As someone at the very least able to break those around her free of powerful magic spells...

Well trained or not she would be a very powerful asset on the battlefield even if the only thing she could do is remove spell effects from those around her. It even has serious offensive potential. Image the impact she would have on the battlefield if she spell breaked the Crimson Empire's equivalent to the Bor's Rageglow. A whole unit of elite magical berserkers charging in to the thick suddenly with no rage, no magically sharp weapons, no berserker strength, and no near invulnerability.