Ok..
She had Personalized Spellbook.
Her spells get more powerful everyday.
She has been alive more days than I have numbers for.
So, her original spell should be powerful enough to knock a civilization back to the stone age, no matter what it is.
But, I bicker pointlessly. Have fun as a newt Marv! :D
“She'd become a governess. It was one of the few jobs a known lady could do. And she'd taken to it well. She'd sworn that if she did indeed ever find herself dancing on rooftops with chimney sweeps she'd beat herself to death with her own umbrella.”
― Hogfather