I originally read that to mean the other 11 Founders of the Order of Hermes, brought to Bonisagus by Trianoma. But now I am not so certain.
I presume Bonisagus learnt something from Trianoma before she gathered the other Founders.
But is it not canon that Trianoma brought the mighty Napolese necromancer Guorna the Foetid to Bonisagus, and she returned to be slayed by her apprentices Tytalus, Tremere, and Pralix, and their allies? I can see Tytalus having contributed something because he expanded on necromancy to summon Titans. But Tremere? What did Tremere have to share that Guorna and Tytalus didn't?
I have been trying to go through the Houses of Hermes books and work out what each Founder contributed. It is not always obvious.
For instance, Flambeau the Founder was illiterate (and presumably had the virtue Magical Memory), yet it is said he did the almost impossible task of inventing a completely new spell. I resume Flambeau shared with Bonisagus his expertise with Ignem, as well as explaining how to invent a new spell (and possibly the bonus for knowing a similar spell).
Actually, Flambeau must have had a very high Magic Theory score. Didn't he turn a large precious gem into his Talisman? That should have required a very high Magic Theory score to handle all the Vis needed to open the gem for enchantment.
Now I am going off on a tangent. If inventing new spells is such a big deal, why was there so many spells known to the Founders?
Unless over the centuries wizards and sorcerers had been learning, then passing on, original spells from good Twilight episodes?
Diedne contributed Spontaneous Magic.
Flambeau or one of his apprentices spread knowledge of Penetration.
Guernicus was a great geomancer, but his contribution was The Code rather than any particular secrets of Terram.
I would argue that Flambeau contributed the ability to master formulaic spells - In HOH:S it is stated that 'after 5 years of seclusion, he perfected a single, powerful attack similar to Pilum of Fire'. No doubt his in-depth experience with his one spell showed Bonisagus how to refine a particular spell beyond its initial power.
I'm pretty sure that the collective experience of the founders showed Bonisagus about the different arts that they specialised in.
Merinitas gave the familiar ritual, and her knowledge of Herbam and Animal.
Guernicus had Terram magics, and otherwise contributed the Code of Hermes.
Criamon is a bit of a mystery, but HOH:MC states that he was a follower of Empedocles, some Greek philosopher - His knowledge supposedly improved more than half the Arts.
Verditus gave item crafting (of course).
Jerbiton assisted Bonisagus in refining the Arts of Imaginem and Mentem, and helped perfect the system of vocal and gestured guides to spellcasting. He also
convinced Bonisagus to name his fields of study the “Arts,” and the capacity to use magic “The Gift.”
Guorna the Fetid gave her knowledge of the longevity Ritual (before being ousted by Tytalus and Tremere)
Not much is said about Bjornaer, except that Bonisagus couldn't use Hermetic Theory to investigate her bear shape. Perhaps he got some insights into shapeshifting, and the essential nature of things?
And of course, Diedne contributed her knowledge of spontaneous magic.
I believe Birna (Bjornaer) contributed to Intellego, think this is in HoH:MC, but I am unsure.
LR knowledge seems to be through Trianoma's and Tremere's raid of the Hyperborean temple of Apollo and the annihilation of its priests, or so it says in AM.
Criamon is directly responsible for Wizard's Twilight, that is, Hermetic Magi's response to Warping, which in general seems much more beneficial than other traditions (which tend to lose their powers, be wounded, become helpless, and generally have a cap of a Warping score of 10, while Hermetics can keep on keeping on, as long as they avoid Twilight episodes.)
Guorna's contributions were probably in line with Tytalus's and Tremere's: Rego and more Rego, spirit control, mind control. Probably why Hermetic magic is so good at controlling demons. However, she wasn't around for too long, so she might have had little chance to contribute.
I think Diedne also contributed to elemental magic, as well as Spontaneous magic.
"Much more beneficial" indeed: on HoH:MC it is said that before Twilight came in, magi just died when experiencing outburst of magic.
About Tytalus, I think his main contribution was more on a political level. On HoH:S it is said that he meddled around with the organization of the order. Also the Lepper Tytalus are pretty good at healing magic.
And about Flambeau, maybe because of him Ignem spells are one magnitude more damaging that any other form attack spells.
I can accept this argument. In fact I suspect that the basic Spell Mastery abilities in the base book that every Magus knows about, were all from Flambeau's Mastered
'Pilum of Fire'.
And yet, I wonder if the Arts were so clear cut before Bonisagus defined them?
Merinita was supposedly a reclusive 'nature' maga, which presumably may have included weather as well as plants and animals.
Since one of the goals of the Cult of Mercury was to help protect against supernatural threats to the expansion of the ancient Roman Empire, presumably their descendants amongst the Founders inherited a cultural distaste for dealing with Faeries. Yet reading between the lines it appears that Merinita was the Founder with the most experience with the Fae, or at least most acceptance of hedge wizards who dealt in Faerie magics.
Yes, Guernicus was the lone heir to a tradition that could create precious metals. So I would add that he probably also contributed to permanent Creo rituals.
And I like to think that in the pursuit of his master's murderer, Guernicus may have been the first person to realise that casting sigils were unique, and developed methods o distinguish between similar sigils.
Prior to Guernicus, I imagine many wizards thought sigils were an unwanted imperfection in their spell casting.
Never forget that Mercere created "Mercere Portals", and enchanted device that held the "Hermes Portal" ReTe75 ritual.
Verditus doesn't seem to have known how to do that, and standard Hermetic Magic can't do that.
While it is suggested that Bonisagus must have helped Mercere do this, I seem to recall there is no documentation by either Founder on the topic.
And many of the standard Durations and Ranges if I recall correctly.
Though it was an Ex Miscellanea tradition that gave us Rings and Circles.
I missed reading that.
All I recall was that quote by Guernicus about the duration of the Order of Hermes being a human lifespan, plus 10 years for Longevity Potion. I had assumed that the different Founders were familiar with different LPs, and Bonisgus put all that info together to create the most efficacious LP.
While the HeartBeast was Bjornaer's primary magical ability, surely she knew some other minor magics? Maybe she had some minor healing potions that gave Bonisagus insight how to make more effective LPs, but History only remembers Bonisagus' frustration/failure to comprehend the HeartBeast.
It might be possible that Tremere might have contributed to Wizard's Communion being so general, since he started as a wizard with a Roman group, then joined a Naples group, and finally conscripted a Dacian group. He must have a lot of experience/adaptability to join in with each group's somewhat unique magical activities.
After all Certamen allows Hermetic Magi to match the strength of their magical abilities regardless of any inconstant training, so presumably Tremere's experience/adaptability provided inspiration.
Bonisagus: Parma Magicka. Also, you know, putting everything together.
Trianoma: Hexing likely contributes to the development of Perdo
Guernicus: Terram magic, possibly some Intellego
Mercere: Broadly, one assumes a sample of Mercurian Rituals Bonisagus did not already have access to, esp. Mercere Portals and, likely, Wizard's Communion. The ability to permanently augment attributes with Creo, as well.
Flambeau: Mastery abilities for Formulaic Magic (Pilum), Ignem development
Jerbiton: Imaginem and Mentem, Method Caster for bold words/gestures bonuses?
Diedne: Spontaneous Magic
Verditus: Crafting of enchanted items, Talismans?
Merinita: Familiar Bond
Bjornaer: Shapechanging, Intellego (keep in mind the unique characteristics still in the house of some of the sensory magic traits)
Criamon: Exact contributions unknown/unpublished, though those of Empedocles were extensive, and it is possible he contributed much of Empedocles' knowledge, as well as the very beginnings of Enigmatic Wisdom, possibly some of the 'structuring' of Twilight itself, as various different hedge traditions have other 'versions' of Twilight.
It's unclear exactly what magical teachings Tytalus and Tremere, Guorna's apprentices, traded to Bonisagus. Both were likely skilled necromancers trained in Guorna's tradition, and are noted as being 'more forthcoming' with Bonisagus than Guorna herself, so I lump them Guorna/Tytalus/Tremere together as 'longevity rituals and some necromancy', with of course Tremere's contribution of Certamen put in their (exact time of integration unknown, but obviously before it was added as a primary dispute resolution mechanism.)
In addition HoH:S suggests that Flambeau was a weak wizard (I think that means he only had a small repertoire of magic spells, unlike Mercere who had many fertility and shapechanging spells/rituals), however his main claim to fame at the time Trianoma sought him out was that he invented a totally new spell - Pilum of Fire. Spell invention was apparently almost unheard of for Cult of Mercury descended wizards.
So Flambeau provided easy spell creation guidelines, including bonuses for similar spells.
I can't recall if it was in 4th or 5th Ed but I recall several mentions that Hedge Wizards are reluctant to give their True Names, because that could be used against them.
But there practically nothing in Hermetic Magic that lets a magus get advantage from knowing a True Name.
There are a few Theurgic initiations that touch on it, but they're largely disappointing compared to their relative investment required, imo.
It's worth noting that in HoH:S, Tremere is compared to Flambeau and Tytalus and considered to be much weaker than either in terms of raw strength - hence the development of Certamen, which once instituted, gave him a domain in which he could match or surpass them. Flambeau and Tytalus are likely to have been selected as examples for their combinations of magical strength and more aggressive personalities, however.
There's ArM5 p.152 Incantation of Summoning the Dead - which hints at the Law of Names.
That law might be very old, and have come into Bonisagus' theory from Guorna and her pupils/victims: Tytalus, Tremere and Pralix. The ancient Thessalian Witches, and hence also Trianoma and Viea, should have known it, too.