What it said about the savior who lost control of her magic + that last panel bodes ill for the future (doesn't look like it'll be all that far into the future either). Wouldn't be surprised if it happens in the middle of the festival where the mc have a hard time not being discovered if she doesn't want to just let countless people suffer/die. Then again, she did give all those high-quality barrier stones to the knights and some of those are going to end up in the hands of the royal family as well. As she is a savior herself, the magic she imbued them with may be powerful enough to shield against the other savior's likely uncontrolled release of magical energy or at least mitigate the damage.