A couple times when catching up I came across people saying that Melkoth's Mystifying Miasma would be easier to learn or at least more suited for Mathilde because of her Warrior of Fog trait, and I'd like to take a moment to refute that.
To review what it does:
U / Melkoth's Mystifying Miasma: The signature spell of the Grey Battle Wizard, this creates a numbing fog at medium range that attacks the combat abilities of the foe.
It's a debuff spell. It uses fog as the medium for its debuff, which is nice because Mathilde likes fog, but the fog isn't blocking vision or awareness or anything- it's just the carrier for the effect. That effect is a "weakens the enemy" effect, specifically setting melee skill, ranged skill, initiative, or movement to the lowest possible value. That's likely accomplished by making them forget how to fight/walk/whatever or very difficult to focus on what they're doing, probably playing off some of
ulgu's associations with forgetfulness or confusion; alternately it might be playing with insubstantiality associations to directly mess with their bodies and reactions making them less solid, or something like that.
So in order to excel at this spell, a grey wizard needs traits which make them good at inflicting forgetfulness, confusion, or weakness. They need to be good at shoving
ulgu at others and messing them up with it in a way that doesn't directly try to kill them, is the point.
Now, let's look at Mathilde's traits.
Grey Magister: You have completed your journeying and graduated as a full member of the Grey Order, giving you both ability and sanction to wield the winds of Ulgu, the grey magic of shadow and illusion.
Enchanter: You have a talent for taming the winds of magic and trapping them within objects. +10 bonus to rolls to learn or use enchanting skills.
Tool-Free Enchantment: You have learned a suite of specialized petty magics that allow you to replicate all the necessary parts of an enchantment workshop.
Windsage: Your magical senses are incredibly acute, and can track magical energies and discern emotions at a glance. +4 Learning, +1 Magic
Warrior of Fog: Appreciation of and focus on mastering the fickle fog of war. +2 martial, bonuses to scouting and hidden gambits while in command, unlocks creation of battlefield spells for revealing or concealing troop movements.
Avatar: You've had close encounters not only with your own God, but with others, and are growing able to recognize and understand divine energies. +1 Piety, +1 Learning, able to sense nearby divine intervention.
Familiar: A wolf named Wolf, a boy of exceptional goodness. Gifted to you by Ranald.
Link of Psyche: The ability to communicate complex thoughts and share mental resources with Wolf. +2 Stewardship, +2 Learning
Magic Power: The magical power that flows from you to Wolf is returned twofold. +1 Magic
Blooded: You've proven yourself in battle. +2 Martial.
Bureaucrat: Paperwork is no longer your enemy; it is now your weapon. +3 Stewardship, -1 Diplomacy.
Brave: You can withstand terrors that make others flee. +1 Martial.
Disdain for Sigmar: Abelhelm Van Hal died abandoned by Sigmar. You intend to return the favour. +1 Piety due to renewed faith in other gods, will not let Sigmarism flourish in institutions she controls - penalty to institutional actions unless worship of another god is instituted.
Interrogator: You've seen what men are made of, and you've seen them unmade. +2 Intrigue, +1 Martial, -1 Diplomacy.
Master Swordswoman: You have blended sword techniques from the Empire and the Karaz Ankor into a style entirely your own. +10 martial when fighting against enraged or unthinking opponents, or when holding a physical choke-point such as a doorway or tunnel.
Laconic: A great deal of effort has transformed your distaste for writing into a brutal efficiency in keeping your writing brief. +1 Diplomacy, +1 Stewardship, +1 Martial, +1 Intrigue.
Court Wizard: You are on the Council of Karak Eight Peaks as the Court Wizard, and have as your remit any magical, mysterious, or otherwise inexplicable phenomena within or near the Hold.
Dawongr: You have been named Dwarf-Friend, and will find a warm welcome in most dwarfholds.
Knight: You have been Knighted by the Elector Count of Stirland, elevating you to nobility.
Magister: You have graduated from a College of Magic and have the right to study and perform magic under the Articles of Imperial Magic, as laid down by Magnus the Pious.
Shareholder: You are a principal shareholder in the Eastern Imperial Company.
Arcane Marks:
Flicker: Light seems uneasy in your presence. Lamps flicker, candlelight dims, and fires burn low around you.
Mantle of Mist: Visible vapours are drawn to you. Fog and mist makes it easier to hide; smoke and gases are rather less convenient. +1 Intrigue, potential trouble with any gas-based weapons.
Unnatural Shadow: Your shadow has a mind of its own, moving around to inspect its surroundings and coil around things and people it takes a liking to. This is, needless to say, very unnerving.
She's got quite a few! But notice that none of them are centered around inflicting debuffs. None. It's simply not something that Mathilde has taken into herself and made part of her character.
In particular, since Warrior of Fog is explicitly related to spell creation, let's take a closer look at it.
Warrior of Fog: Appreciation of and focus on mastering the fickle fog of war. +2 martial, bonuses to scouting and hidden gambits while in command, unlocks creation of battlefield spells for revealing or concealing troop movements.
There's fog in it, and Melkoth's is a Miasma, right? Well... no. This trait is explicitly about the fog of war as a conceptual idea, which is why it related to scouting and hidden gambits. Something like Cloak Activity, which is basically "Caster Does A Hidden Gambit: The Spell", would be far more likely to gain bonuses to learning and casting (which it didn't, probably because related traits don't give spell learning bonuses; side note, I am super sad that we don't have Cloak Activity because it's very well suited for Mathilde and a great enchantment seed) than Melkoth's, which creates mist which, going by its Warhammer Fantasy Battles effect, doesn't even obstruct vision- it's just a carrier for an attack.
In other words, Melkoth's contains basically none of the associations that Mathilde has traits for.
The thing she
does have which makes her closer to it conceptually is this:
M / Universal Confusion: Bewilder, but applies to a whole group at once, up to about a ten meter diameter. Short range.
Mastery - Cloud of Confusion: You can cast the spell as a billowing cloud of bewildering gas, which pours from you for several minutes, constantly effecting everyone nearby.
- Mathilde can cast both the normal spell and the Mastered version. Both are indiscriminate, but the normal version applies to anyone within that radius at the time of casting, whereas the Mastered version continues outputting the gas over minutes to effect everyone touched by it.
- The Mastered version does not need to be inhaled to take effect. Mathilde is immune to it, as is Wolf; everyone else will suffer from Bewilder unless they're strong-willed enough to shake it off.
Mathilde's Mastery version of this spell is very close to Melkoth's conceptually because it's also using a conjured physical mist as a carrier for a magical mental debuff, with the primary differences being in type of debuff and scope of the spell. If we want to be drawing lines connecting her existing skills to Battle Magics when deciding which ones to learn, that would be a much better place to start.