This story is a sequel to School Daze

Cheerilee and Screwball expected a quiet Ponyville vacation. But Discord's back, and he's come for the children. Can Screwball and the Ponyville teens overcome the Lord of Misrule in their worst nightmares?

A creature has risen out of the waters near Manehattan and seems to be hell-bent on reaching the capitol city of Canterlot, destroying anything in its path.
It must be stopped, no matter the cost.