Click on the mana display on the top of the screen. It will show you a list of enchantments. Also can be accessed from the Kingdom Report.
I do not see it there. There are only city spells, I do not see unit's spells in kindom report. I am sure that the spell is cast because it says so in my spellbook (i.e. I can not cast second time because the "spell is active") but I can't find anyway to stop it, or even to see that one mana per turn is indeed subtracted from me. Is it part of the bug?
