@masukomi
I've started to see how much I can squeeze out of the concept of 'witches'. There's plenty of source material lying around here in Serbia - they have their own version of 'baba yaga', and a general healthy respect of babas.
Add in a little life-twisting magic, and it's naturally lead to 'mother of monsters', 'swamp-hags', and and a slew of other tropes, plus some new elements.