[Miller]

After recent testing, I've learned that Magia Detremus isn't accounting for bonus SAN from Aptitude for the sake of reducing the HP reduction provided by Magia Detremus.

https://i.imgur.com/Fd4pSEg.png

(Total HP is the HP I've calculated, while Actual HP is the HP displayed in game.)

As shown in this image which calculates the total HP with
((SAN x 2) + (Base STR x 3) + (VIT x 10) + Spent Points + Flat HP Boost) * Reduction (30 - 1 per each 2 Scaled San)

The numbers are equal when rounded down for the final result but start to differ once enough APT is in play, (Displayed by the fourth calculation and downward.)

However, upon plugging in the would be reduction if bonus SAN from Aptitude wasn't in play specifically for Magia Detremus (While accounting for the HP provided by all SAN)
The numbers wind up being equal to the values displayed in game.

https://i.imgur.com/awPaHue.png

Notice how the numbers are equal to the values that were displayed in game.

[Miller]

In a new example made on the test server, this character has exactly 1 base STR, 22 VIT, 8 SAN and 61 invested points.
3 + 220 + 16 + 61 = 300 total HP.

With 8 SAN, my reduction should be 26% of 300 which is roughly equal to 222 HP; however the in-game example gives me 210 HP, which is what it would be if the reduction was 30% of 300.

[Neus]

I don't believe this is a bug. APT stats are treated as bonus stats now, while Magia Detremus only applies the base SAN.