I also considered this build, here are my additional thoughts about this:
Thaum3 is one of the the best classes, however, the big disadvantage
is the buff limit, so you really need to partner up with a Krivis
with Daino to increase buff count limit. This class is an
offensive support class, and not going Thaum3 is a waste because
you are not capable of maximizing all your swell buffs.
Going full Int will give you the best conversion of invested stat points
due to +10% Int bonus per rank. If you use Transpose, you will be going
frontline (INT->CON).
Your Transpose will last 190 seconds if you learned maxed Swell Left/Right/Brain,
you will only have Lv.14 on Transpose and Lv.1 on Reversi.
The total buffs you will get from those 3 swell buffs (including maxed attributes):
Physical & Magic Attack: +304, if wearing dagger, additional: +260
total of: +564 magic & physical attack
if you are a magic class, add swell brain buff: +145
so that can end as: +709 magic attack.
Additional physical & magic defense if wearing shield: +271
In my opinion, it’s best to go Wiz3->Thaum3->Warlock, and get a permanent
Krivis partner so that their support buffs and your offensive buffs will
bring the best synergy possible. I also expect better skills coming from
Warlock2 in the future update.