[@Kost Alter]

The primary issue here is the lack of information we have on the Ainsworths in Prisma and thus my hesitance to introduce them to the roleplay at the current time. If Prisma was further along then I'd be more receptive, but as it is with our limited knowledge on them, that's a very iffy proposition. Moreover, given whom the Ainsworths replace in the Miyuverse and the fact that said family very much does exist in the world of the roleplay, I'm altogether shaky on this. I'd heavily advise pursuing something non-Ainsworth in nature; you can use a family that specializes in Displacement, but the Ainsworths in particular have a lot of baggage we've yet to unpack, so I'm viewing them in a similar light that I would with say, the Strange Fake cast. Though obviously different given Prisma's status, but still.

A serum that would suppress the conceptual mind of a thousand year magus would be something absolutely incredible (and would require knowledge that he blatantly doesn't have), and moreover would probably result in myriad negative impacts. Moreover, we don't know that the means by which the conceptual mind is retained are a curse (and I doubt that's the case, but that's a different matter). 

Ainsworth-tier Displacement is suitable for an Ainsworth; however, that's still problematic for reasons already given.

[hr]
She doesn't have something like Asterios or Gorgon's skills, so STR to D, AGI to B. 

The parameter increases from Monstrous Strength won't be continuously active since Monstrous Strength isn't continuously active. You can make it continuously active, though. 

Expound on applications of the Oath skill beyond LCK checks. 

Keep in mind that massive manipulation of water will have a corresponding prana cost. 

The second NP is pretty baseless and I'm guessing you acknowledge that, given that you're taking "first girl molested by tentacles" and turning it into "girl who can control tentacles that ignore all defenses and trigger mental interference on the target". You can use the Medusa justification of "but Medusa uses the stuff that fucked her over like Bellerophon and Harpe too", but that's only really allotted in my eyes because those are canon.

Most importantly, I have no idea why she's a Caster when she has no magical ability whatsoever. Even the water manipulation isn't magecraft (artificial mystery) so much as an ability inherent to the Phantasm Races (natural mystery), so she doesn't qualify anymore than, say, Ibaraki would.