18 point mana drain from scroll writing - bug or feature?!

[shockeroo]

My mana stat was just dropped from 19 to 1, writing a scroll of defense using a blessed writing set on a cursed blank scroll - is this right?! Probably the third defense scroll I've written this game, but the first in a long long time. I was expecting a couple of points of mana drain, but this seems a bit crazy? I'm a L49 Gnomish Bard.

[_Ln_]

Cursed scroll is what did you a lot of damage. There are some additional rolls that you can fail even with a high-level high-skill char which can further increase the cost. Finally, defense/protection scrolls are relatively hard to write on their own.