Sunny had hoped that his initial guess was wrong.
Perhaps there was a limit to Rain's Flaw… something like only being unable to kill those who were defenseless, weaker than her, or maybe those who did not represent a fatal threat.
Perhaps it was even dependent on whether she believed that the enemy deserved to die… although that one had been disproven almost immediately, since there was no sane reason to show mercy to a Nightmare Creature.
However, after capturing a few more abominations and forcing Rain to confront them, he had to admit the shocking truth.
[You cannot kill.]
Sunny was not the Nightmare Spell, but if he were, he would have described her Flaw with these three words.
As the truth dawned upon the three people gathered on the clearing, they remained silent for a while, each trying to cope with the stunning revelation.
Sunny felt as if he had been smacked in the head with something heavy.
He was dismayed.