D'Hofrryn: “What is that, a Woodlow Transmogrific Spell?
Aud: “Thornton's Hope
— D'Hoffryn and Aud[src]

Thornton's Hope was the transmogrification spell employed by Aud to transform Olaf into a troll. Aud employed eelsbane as one of the spell's ingredients to get the "troll" element. It was her initiative in using this spell for vengeance that resulted in her becoming a Vengeance demon.