To improve some energy work and channel the energy of Death into the target is it a plan to burry hearts of dead animals bought from local stories near her? Or maybe throw them too in the bushes near her place? This energy is very dense and probably suitable for a death curse?
Are animal cemetery as powerful as human? Their dirt is very powerful than very useful for witches right?
Animals tend to be for me gentler than the humans. I just had this flash of inspiration why not create a doll of flesh and bones… bind it, curse it, drug her, inflict it with ailments of the most painful uncurable kind. Find and ant hill and stake her there over looking her human. Ask or whatever rodent you have in mind to finish your work. Oh my i seem to have a vengeful bone or 2.