Ok, this is a example a bit more extreme than what I originally thought (you had it rough), but it does get the point across.
Yeah, but you would also make sure that the location of the magic circle/artifact is a kept secret to avoid just that or you could straight out hide the very existence of it and just reveal it to a few, high ranking individuals.
And while having a powerful giantess as the “anchor” does make sense, it seemed to me at least that Kendra/Maryen’s mother was quite the trigger happy person (like I understand not liking your daughter’s friend, but ordering a hit job on them is a bit excessive), and they had various wars with homaspernia so if anything happened to her, they wouldn’t even had the time to salvage anything.
It’s not always the best ones who survives.