If one were to have a huge-ass grudge against eldritch beings. And possibly wanted to go to a site where one had manifested once before. How much local history would possibly be available to that someone, if they had experience with/knowledge of some versions of eldritch beasties in their infiltrator history?

And as a follow-up, if that infiltrator wanted to, say. Summon something nasty with the intent to kill it dead. Is that even possible? And how quickly would she die if she did do it? :P