One thing you could do which could be quite disgusting if mommy is in danger of being overwhelmed is have her give birth in combat to something(s)...
Having a zerg rush defense just when you think you've got the big bad trapped, the PCs suddenly face a swarm of newborn things. Play up the horror if Mommy Hannah has been using human and other DNA a newborn human baby (babies) piteously crying while it (they) sprouts various venomous clawed appendages and transforms into face hugging, flesh ripping horror. Even better if there is a female PC/NPC that goes to comfort said crying infant(s) just before the horrific change happens...
Maybe Mommy Hannah can summon normal creepy crawlies, several thousand centipedes, millipedes and other vermin, which might be venomous can really add to 'ick in 'magick'.