The Princess in Black and the Hungry Bunny Horde #3 by Shannon Hale and Dean Hale illustrated by LeUyen Pham*

On their way to eat breakfast with Princess Sneezewort, Princess Magnolia's monster ring goes off.  Frimplepants, her pony, is quite disgusted with the interruptions as he had skipped breakfast in anticipation of the delicious spread with Princess Sneezewort.
Then Princess Magnolia and Frimplepants undergo transformation and are The Princess in Black and Blacky, her faithful pony.  When they arrive on the scene of the monster invasion, The Princess in Black is surprised to view cute, innocent bunnies munching the goats' grass.  Blacky and the goat boy, however, see the bunnies for who they are.  Who will be able to convince The Princess in Black, otherwise?
I like the twist in this one, #3.    The second one was too similar to the first one.   I, however, like this one as much as the first one!
*Highly recommend (for transitional readers).
*Borrowed from the library.