As soon as you get to the monastery, at the magician who drives wine, you can buy a zauberstab staff, requiring 25 mana and adding 20 to it. We dress this staff and turn into someone with the help of a scroll, and then back. We see: Mana did not take himself, and the rapier appeared in his hands (well, or that another). Remove the rapir, wear staff. +20 to mana! Thus, each transformation scroll is +20 to maximum mana! I discovered this bug at the end of the game when I killed the last. I had 13 scrolls and 298 mana. I finished from 558!