Greedily absorbing the mana, Sarah then quickly retracted her orrery. Still shielded by a spatial barrier, the girl might have offered the enemies surrounding her a witty comment, however, as she had issues speaking with strangers, she could only awkwardly observe the still attacking opponents, while she waited for the mana to drain into her spell.
Fortunately the barrier held so far.
 
Then noticing that the flood of mana was slowly subsiding, it was time to disengage. She had  what she could get from this location and she would now just lose mana the longer she stayed. The barrier was technically sustainable with the collected mana, even without the spatial mana crystal, but that would go against the reason she collected the mana in the first place.
 
So the girl sacrificed the outer edges of her orrery to speed up the compression of the massive spell circles of her skill and, once everything was within the area of distorted space, she unraveled the twisted dimensions.
Then, from one moment to the next, they were within a cave. If time had slowed down, they might have even caught glimpses of various other locations she had added to the distortion to serve as a secondary, tertiary and so on base.
But bases which were now irrelevant.
 
If one were to look around their current location, countless engravings could be seen, decorating the walls, and also an entrance to a connected cavern, which was however sealed with rocks.
Apparently no one had been here. Sarah had hoped that would be the case, as all the spell had been lying dormant without her being nearby and powering them. Though even if someone else had found this room, the engraving had little to do with the actual ritual. Well, she needed some of the engraved spells, though in the worst case she could also just recreate them from her memory.
However the spherical cave with the ritual itself was hidden below their current position and had lain similarly dormant until the spatial distortion had been resolved, returning missing elements of the ritual and more importantly the mana the mage had collected over the past days.
 
Though she wasn't starting the spell just yet. Checking the amount of mana again, she was now close to what she expected to need, but still not quite there. She could try to wait for a couple more hours, but then she would just risk being found. Who knew what skills and spells her enemies in this war could have. While it was unlikely that the beasts would locate her on their own within the remaining time, humans were different and her defenses weren't intended to be used against them.
 
But that didn't mean she was out of options. So going through the things she had, she started to sacrifice.
The last remaining drops of mana in her crystals? Offered to the ritual.
Most of the souls in her orrery? Now gone.
A good chunk of her own health? A resource she would recover in time.
Her arrowheads? Now junk, but she could maybe add some spells to her orrery later. Once she started to refill it.
 
If her soul hadn't been as crippled as it was, she would have also cut out a chunk of that, but she was still recovering, so there wasn't much she could do with it.
However she still wanted more mana.
Needed more mana!
 
Should she sacrifice her clothing? They didn't have special properties, aside from those usual in the Realms, but she could probably squeeze out a few points of the needed resource. But no. It would leave her even more defenseless than she already was, with her very mentally focused attributes and she didn't have a way to get new ones. The loss wasn't worth the rather limited gains.
 
But she needed more!
 
If she had more souls and bodies... But there weren't any enemies around and if they were, her sister and Nia would likely not be able to defeat them, even though they had increased their levels.
Though...
 
She just needed souls.
 
She just needed mana.
 
Taking a bit from her allies wouldn't be that problematic, right?
They would recover.
And no enemies were currently around in their sealed cave, so getting everything done faster was better.
 
So having justified her actions to herself, she quickly turned to the two girls, which were still standing close by and monitoring the environment for uninvited guests.
Then using the pitiful remnants of her orrery, she grabbed most of the souls floating around her party members. Obviously such an action didn't go unnoticed and they were voicing a few complaints as their aura lost some stability with the suddenly missing souls. Though, similarly to how damage to her own orrery didn't influence her much, the loss of those souls only translated to a worse mana recovery rate for Sera and Nia.
Ignoring the complaints, Sarah sacrificed the souls and returned her focus to the two.
 
They still had some unused mana she could take!
 
But the "how" was the question. Contrary to her previous experiments with the sacrifice skill, she didn't want them to die and only take some of their excess mana they weren't currently using anyway.
However, regardless of how she thought about the sacrifice skill, she couldn't come up with a good way to use it in a non-lethal way. Sure, she could sacrifice parts of her own health, but that was for herself. Getting the skill to work on someone else was already hard enough and then they usually died pretty fast with little control. It was a good way to make sure, whatever she was targeting was really dead, but that was it.
 
Though maybe her approach was wrong. Quickly going over her skills and their descriptions, Mana Harvesting could be another way to tackle the issue. It already provided her with a vast quantity of mana and seemed to affect those around her. So what would happen if she somehow focused on the secondary effect?
 
Being on borrowed time, she couldn't think long about how she might empower and evolve the skill, so she simply enacted the first thing which came to her mind: She tried to recreate the state of her old world inside of her body by intentionally mana starving it. A state easily achievable by sacrificing some health, enduring pain and pushing as much mana as possible into the ritual. And even if it wouldn't work out, she would at least gain some more mana from herself.
 
So she placed a hand on Nia's shoulder, receiving a questioning look from the other girl. In most cases Sarah might have explained a bit about what she was about to do, however she didn't have the mental capacity for that. Even with her overmind skill, the pain from her soul and body had to be suppressed, the ritual had to be guided, her orrery had to keep the mana from the environment under control and most importantly she had to focus on the flow of mana in her and Nia's body.
 
A metallic taste spread through her mouth, though she ignored it. As she did with the messages from Eas, which appeared from time to time. Maybe a skill had leveled. maybe someone had died and she was skill credited for it.
 
She didn't care.
 
She just concentrated on the flow.
 
Until the wall crumbled.
 
Only a few moments had passed, yet it felt much longer for her, as finally mana streamed back into her own body. Not from the environment, but from the other girl. And another message had appeared.
This time she actually checked it, as she wanted to make sure she understood what she just accomplished.
 
[The Mana Drain skill has been derived from your Mana Harvesting.]
 
[Mana Drain]
[Greed beyond greed had led you down what some might deem a dangerous path. Seeing even those close to you as well as yourself as expandable resources, you willingly offer up whatever you can to reach new heights. Going far beyond what others see as normal, nearly destroying your own body, your flesh has finally become closer to your mind. Accepting your hunger for more, it too hungers and will take whatever it can to feed your ambitions. Mana regeneration increased. Touching other unbound, unequipped or similar entities with higher mana concentration than your environment will drain them of their mana. This does only affect their normal mana pool. At the moment.]
 
"Hey! What was that! Did you just take my mana?!" More complaints from the guide. Though Sarah ignored them. She was close. So close.
Turning to her sister, the warrior had apparently already sensed the dangers which were about to befall her and tried to distance herself, yet she wasn't far enough away and so she was quickly grabbed and more mana was drained.
Well, not all. Sarah knew when to stop. She was pretty sure the ritual had now enough mana.
 
And so she unleashed the spell while also activating the specialized barrier engraved in the walls around them to defend themselves against the fallout.