Realms of Eas

With the party entering the second of the ten floors, Sarah gave up on finding a way to deal with the fog.
For a water based solution, she would need to be closer to fog, which would defeat the purpose of the request. Pressure and temperature were easier to influence over a wider scale, but that fact was also an issue as the effect was harder to contain and needed therefore a lot of mana. Maybe someone with an affinity, like her sister, could help improve the spell, however, while that could half the mana cost compared to her amateur non-water-based spells, they still had to affect an area of more than one square kilometer.

Shifting her focus back to more productive questions, she decided to shelf the issue with her magic in combat for the moment. She hadn't seen a pure mage so far, but everyone used just the most basic type of elemental effects when fighting. Effects even her sister could invoke. Though that fact probably had something to do with the system granting intuition based on the chosen affinity and that Sera liked to act on feelings.

Next, they needed defenses. In their old world their personal abilities as well as law enforcement units would have been enough. Unfortunately, in this one, thanks to level and magic, a lot of powerful beings existed, which the twins had to fight to increase their own levels. And even if that wasn't the case, with powers blocking access to certain knowledge Sarah was bound to clash with some of them sooner or later.
Simply teleporting away seemed like the easiest solution, but, with spatial bags commonly in use, items with such effects probably already existed as well as countermeasures against them.
She could also just create an item with some of the defensive options she implemented for the summoning. However then she had again the issue with mana. Strengthening and shielding body, mind and soul didn't seem that easily achievable. Besides, she never had opportunities to test it against the dangers of this world. Her brief visit to the beyond, which she couldn't remember, and Eas creating new bodies didn't count.

Watching another fight against some bats, Sarah pondered over her options. With the resources they had, creating good defenses against physical attacks were hard. Pure magical shields and armor would have the usual issues, while they were missing the material for other types. Maybe enchanting the armor they were currently wearing was an option... Though, with Sarah only being confident in working with metals and her currently fighting sister being the only one with more than a few accessories from the material, that would have to wait for later.

Mental defenses were covered by the ring, according to Nia. Yet how well it worked was another question. The engraving was a bit too complex and out of her usual fields of expertise to decipher on the way. However she could make some guesses, as healing magic, which worked similar to mental magic, could still affect the wearer. It either blocked some specific applications commonly used by mages with the affinities or it didn't prevent the magic and only showed that there was an illusion of some kind.
Not very reassuring, but with the given limits she also couldn't think of anything better for the moment. At least as long as healing magic should still have an effect.

Finally the greatest issue was some kind of defense for the soul. Regardless of whether some people with actual soul affinity hunted them already due to her new skill or not, with how low her sanity attribute was, she needed ways to prevent a further reduction.
But how does one defend the soul? How would one with soul affinity even attack? Crashing two souls together sounded like a bad idea, unless they had spare ones…
Now thinking about it, wasn't that already a solution? It wouldn't matter how someone with soul affinity attacked, as long as they had enough spare souls to defend from the attacks. They still needed to retaliate before the defense was exhausted, however that was an issue with every kind of defense. But she concluded that adding some way to identifying an attacker would be good.

Or she could just hurl some of the spare souls back, if that worked...
Sarah could only cringe at that thought. It sounded very unscientific and like something Sera would have come up, if presented with the same problem.
Not acting on the impulse, she decided to contemplate her options further. There had to be something better.

In the middle of the third floor she shelved the issue. If she wanted to go with the spare soul hurling approach she would need a lot of souls. And that for two... maybe three people. The sooner she started to collect those the better. Besides, there were other applications for souls. Though how would she be able to store souls and later reuse them? Concentrating on the ring she could sense the faded shape of a soul. Her own soul was much bigger in comparison, however also faded.
Between the fights she had also managed to see but not see, whatever one wanted to call the additional sense, the souls of her teammates and dead enemies. Unfortunately the range of her new sense was only two maybe three meters around her. All were faded and their size seemed to relate to the sum of the current sanity and total mana pool. Though the former was just an assumption based on the fact that her soul should have been much bigger otherwise.
Hopefully the skill would give her a better impression of the souls once it reached higher levels, but for the moment she had to work with what she got.

All souls except for those of the dead beasts were pretty much fixed in their position. For the three humans it was the head, probably the brain or some part of it, while for the ring it was its complete shape. For the beasts, the souls were still in the skull, but seemed to lag. As if there was a disconnect between body and soul. Furthermore they appeared to be shrinking and smaller souls had a higher lag.

Under the nagging of their guide she pulled herself away from the body.
Sarah would have liked to study it a bit more, but doubted that there would be any more insights to be gained for the moment. The dissipation of the body would probably start once the soul had reached some threshold, but that wasn't what interested her anyway.
How could she stop the shrinking of the soul without binding the soul to an item? Breaking rings, which took some time to make, wasn’t what she would call an easy way to reuse souls.

With the creation of ensouled items being too complex for the moment, she needed to change her approach. How could she efficiently capture souls? What prevented or forced souls to shrink in the first place? Well, it was that they were taking sanity damage, but what was the cause of that?
Unfortunately Sarah had only very few data points. Souls bound to sentient beings and items would survive. The same was most likely true for plants too, though she had to rely on Nia's statement in regard to that.
Damage would then be taken once the host had died or when one perceived certain impressions. The mage didn't like how unscientific all those vague statements were, but without tests she could only theorize. It also left a few questions open. Would death allow a soul to perceive the damaging impressions? Are the damaging impressions similar to what would happen upon death? Is it even a causality that death causes damage to the soul?

Pushing all those questions aside for the moment and onto her ever growing list of things she wanted to research, Sarah focused on what her ensouled ring and a living body had in common: flowing mana. Maybe she was missing something, but as a metallic engraved ring could serve as a vessel like a complex human body, the one similarity between the two stood out.
It would also explain why souls could influence mana, it wasn't so much some random ability but a necessity. Why couldn't souls use that ability without a vessel? It could amplify the ability. Basically once the vessel vanished a soul would shrink until it could sustain itself again. This would also mean that the existence of mana in their old world wasn't a coincidence. Without mana no soul could have existed there.

Again, there were a lot of assumptions. But her theory looked logical.

Sanity damage from mana overuse? The mana flow of the body was redirected to a spell or something and the soul starved.

But in the end, the theory didn't have to be the truth. Only the aspect that souls could sustain them-self on flowing mana was relevant for her at the moment. A flow which could be amplified by the body or her artificial ring.
As long as she managed to provide the mana flow she should be able to collect some amount of souls. If she could further adjust the flow dynamically, it should be possible to extract and insert souls at will, without breaking items.

The question was now how to test out the validity of her conclusion. With them being still in the middle of clearing the dungeon the scientist couldn’t just start carving spells into the stone. During fights they were too easily damaged and they had to move outside of them.