I'm working on a reincarnation story where the characters start out in Germany (specifically Bingen-on-the-Rhine) in the 700s, and end up, after several incarnations that end in blood and death, in 2011. The reason for all this born-again-ness is that one of the characters, knowing she was about to be executed, cast a spell to ensure that she and her lover would be brought back to life (she assumed it would be a few years later, but the spell sort of backfired on her) which sent them off into a neverending cycle of rebirths.
The trouble is, I can't for the life of me seem to find any resources on what spell- or even what magic/folklore belief system- my character might be pulling on when she casts this. I've tried Googling "medieval folk magic," "German magic," "folk magic," "German folk magic" and "reincarnation," and the closest thing I've managed to pull up is
this subsection in Wikipedia, which, while interesting (if geographically off-centre) in a cultural sense, does not tell me how a common magic-user might go about DOING this. Does anyone have suggestions? Links? Arcane spellbooks?