I have this concept for a demon, and I am not sure if this is too out there for a first circle. Their main gimmick is animating a statue and giving it the ability multiply itself by eating similar things.

For example, if the summoner used a ruby crab statue as the ritual anchor/vessel, it would animate the statue once it ate enough crabs of rubies it would split itself into two identical golems.

The idea is that there are a bunch of things like that in a buried factory cathedral. They become a problem by escaping their containment and start a famine by eating the local animals.