a spell(spontanious until compiled)is a creoaniaml(terrum)spell that creates a animal trapped in a hailstone!
also in meadeival time they had a fall of mice!(I forget were I read about it,but I know it's true)
Charles Fort
Obviously , you have been getting your source material from authors like this.
You may want to check out the links at the bottom of the page ,
they should provide many hours of fun reading.
And they are all true!
Or to scare the peasantry away from the area for all future... Add a creo-requisite and have it rain blood. Not only will it be deeply disturbing and horribly smelly... it will also ruin the crops.