Then, I opened a Pandora’s box, which supposedly gives 999 mana, and…
It subtracted all the mana exceeding 999 :), leaving only 999. That’s how it works…
You can only get more than 3960 mana if you have a specialist in intelligence (like Eleazar); at level 88, he had about 12600 mana. I couldn’t reach a higher level this time, although my record level is 32767. After level 75, adding experience causes strange effects, and I haven’t figured out the patterns.