An analysis of how the Summoner job's magic works (Spoilers through DT)
Preamble
Hello this is a topic I just find fun to think about, so I wanted to write it down! I will be going through Summoner lore itself expansion by expansion, but I will invoke lore from future expansions if it clarifies/strengthens my interpretation of a prior expansions' lore.
So spoilers freely abound you have been warned!
That being said let's get to my nerd ramblings.
The beginning-Arcanist and Summoner relation
-Summoner is one of the two offshoot Jobs from the base class of Arcanist (whose magic is called Arcanima). Though the Summoner magick tradition doesn't have a direct continuity with it the same way Scholar and Arcanist are shown to have in the Aloalo lore, they do use similar glyph and math-based techniques, as evidenced by Ruin 3 also being used by "The Lala" boss in Aloalo.
-Modern day Arcanists prefer to create their familiars' using gemstones as the focus in the familiars' creation, the Carbuncles (this will be relevant six expansions from now.)
ARR direct evidence- When things were simple and straightforward
-Summoning Magick was created by the Allagan Empire to fight primals
-When a primal dies, it disperses its "essence" to those nearby, that essence can then be used by a skilled enough mage to create an egi-familar. Thus does a Summoner need to be someone who was at the defeat of a primal
-Creating an egi requires travel to a land saturated with the right kind of aether to align the Summoners body with that aether, for example being in the Sagoli desert to align one's aether to fire.
-The egi created does not in any other way require a physical focus
-The created Egi must be battled to be commanded, similar to other powerful familiars like the mother porxie of all things.
-Summoner is the only job quest in where there is a direct ascian or even implied ascian involvement.
ARR analysis
-Summoner's magick lore is quite straightforward, kill primals to gain the ability to summon Egi's. It will not stay that way, but even now there are a few points of note.
-What exactly a primal's 'essence' is will be easier to clarify with evidence later, but it is an important note.
-Egi's being the only modern familiar creation that does not need a physical focus is actually incredibly important. Carby's need gemstones, porxies need water and clay, Silkie was made from a broom, even the scholars jobstone probably counts for the fairies. I'd say that the necessity of a physical object when making familiars is the key distinguishing trait between modern magick and creation magick. Why Summoner does not require that will be easier to theorize on later.
-The presence of ascians in the summoner job quest, does carry the implication that the study of it could lead to secrets the ascians may not want mortals to know, hold that thought for later.
Heavensward direct evidence- Things don't change much
-There is a limit to how many Egi's a mortal summoner can have, after that limit is reached the ritual simply won't work.
-To circumvent that limitation, Summoner's can perform a ritual to acquire a trance, a state that uses the primals power to strengthen the summoner instead of creating a servant.
-Carteneau is chosen as the location for the ritual as it is an area washed with specifically Bahamut's aether.
-A lower Ascian serves as the main antagonist of the questline
Heavenward analysis
-There's not much to say about the Heavenward lore on its own, it's quite self-explanatory. But the continued importance of Ascians, and the idea of Summoners utilizing a specific entity's aether (instead of a more general fire, water, etc), will both be important to my theorizes on the next expansions lore.
Stormblood direct evidence- Lorebombs galore and none of it is really explained
-In exactly 1 solo instance you fight "demi-wyverns" and these wyverns are described as "not being egi" this is the only time Demis are described in game. Those Wyverns were summoned with summon magic
- As time went on, Allagan summoners transitioned from using books to technology as their foci for magic, culminating in master Sari creating an ai summoning machine that did not suffer any limitations on how many egi it could make.
-Said machine made an Egi of master Sari, a normal person, after he killed himself near it. And plans to make an egi of the Wol by killing them.
-The capstone of the questline gives the wol the peak of Allagan summoner knowledge, which goes undescribed in text. In every expansion up to present day, this unlocked access to Demi-Bahamut
-Ultima summons "demi" versions of the alliance raid bosses, which pop in to do an attack and then disappear. She also has a connection with ancient Allag
Stormblood analysis
-Stormblood fundamentally changes the concept of what a summoner even is, and does so casually without real elaboration, but it also doesn't call out the machine as breaking the usual rules of summoning besides the egi limit.
-Therefore, due to distinctly non-primal wyverns and people being eligible to be demis and egis, that summoning magick is actually not restricted to primals at all.
-Instead it appears that whenever ANYTHING dies in the ffxiv verse, that thing will stain the surrounding area with its aether. And those stains contain a blueprint, or concept if you will, of that creature that summoning magic can then use to conjure a servant copy of it.
-Given the egi limit, it seems that this knowledge was only passed down to the most powerful summoners, as it was simply more efficient to use primals for limited egi slots instead of random people for instance. Therefore, I'd posit that the "ultimate knowledge" the Wol gains in the final Stormblood quest is both this knowledge, and the knowledge on how to make Demi's.
-As for how Demi's work, my interpretation is mostly based on game mechanics on Stormbloods release, boosted by Ultima summons working similarly. Demi's use that same 'concept' of the creature and a lot of specific aether compatible with it, to create a temporary summon instead of the permeant servants that egis are. (This also lined up with how demis vs egis worked in game till endwalker)
-Perhaps Utlimas interacts with Allagans is how the top summoners figured this out?
Shadowbringers direct evidence- No more job quests, should be shorter
-Phoenix trance and Dem-Pheonix are things.
-Primals are specifically called during msq as being the closest thing in the modern day to creation magic
Shadow bringers analysis
-A thought that occurred to me prior to thinking about summoner magick more deeply "If primals are just creation magic, which can make anything, what unique about them allows them to be used for making summoner summons?" this could be a plot hole- Untill I remembered the reveals in the level 70 job that there is in fact nothing fundamentally unique about them, anything can be used for summoner summon. Primals are just strong candidates
-The Summoner jobs closeness to creation magick might also help explain why the ascians were particularly interested in stopping the wol from gaining more knowledge in it.
Endwalker and Dawntrail evidence
-the gemstone primals are summonable
-Game mechanics change to involve personally using the power of the primals for all summons
-The Lopporits specifically describe primals as being creation magick that replace requiring concepts with fervent belief, with a touch of intentional ascian sabotage around tempering
-Solar-Bahamut is a thing
Endwalker and Dawntrail analysis
-First off I'd say the Lopportis description of how primals work i think lends credence to my interpretation. Primal summoning substitues concepts with faith, Summoner substitutes concepts with the 'blueprint' the things that have died leave on your aether.
-For the gemstone primals (Ruby Ifrit, etc) I'd say this is an instance of the wol using modern day arcanima to augment their summoning. Summoning a ruby carby involves flowing aether into an actual ruby, So summoning a Ruby Ifrit likely involves flowing Ifrit-Egi's aether into a physical Ruby. Lorewise, outside of present game mechanics, this would likely mean the wol could permanently have an ifrit or Titan walking around with them if they wanted.
-And Solar-Bahamut........Look it's a new model so, like the machinist's machines got in the last lore book, it will probably be described more in the encyclopedia eorzea that comes out after Evercold. I have headcanons but they're based in nothing even vaguely established in actual cannon.
Conclusions
I think I've made a very fair case for Allagan summoning actually being creation magick just limited to things you've killed before, and that fact means it's actually an art with use in the modern of the ffxiv world even if primal summoning goes extinct. Primals are conveniently powerful, and also clearly elementally aspected, creatures that are can be around to die multiple times- That makes them the ideal targets for Allagan summoning.
BUT they're not only options, as long as the world faces powerful entities strongly aspected to an element that means summoners still have a use case. For instance, as long as strong voidsent remain a threat? Seems like a source Egis in the making to me.
And the thought occurs that Tural has a perpetual problem of powerful animals beefing with people, seem like the prime spot for a school of summoners to turn the power of defeated foes for the common good. Which is in fact a head cannon of something my Wol canonically does now
TLDR- HOLLY YAP
Summoners use creation magick, but it's limited to guys they have killed before. Therefore, the Wol should get Alphy to lock in and create Emet-Selch-egi thank you for coming to my Ted Talk.