Transforming a complex and highly difficult body double replacement spell into a curse binding that everyone could use.
This could also be considered a kind of 'black box' handling of spells—the user does not need to know the complex principles but can still use it successfully.
This idea of turning spells into curse bindings did indeed give Annan some thoughts…
"However, since it's a curse binding, there must be a possibility to break it, right?"
Annan looked up and inquired of Naifertali.
After all, they were not true spellcasters.
If something went wrong, they couldn't make fine adjustments—for instance, the person inside the mirror could modify "Giralda's" appearance and body shape and could either strip away or bestow more power. But Annan couldn't do it himself.
Because he was only a user.
"That's right."