Next Halloween their should be a great pumpkin event chain.
I would revolve around one in a pumpkin patch that with a pumpkin that grows over the course of the event chain. The pumpkin will evolve over the event into a scary looking jack o’lantern to size of a small building. And then lifts it’s self out of the ground by it’s roots and starts attacks everyone with it’s thorny vines.
*pumpkin patch should be in a scary looking area with energy in the air and coming out of the ground.
*the great pumpkin would attack with poison form it’s vines. And throw pumpkins at the players.
*Parts of it would be on fire because it’s a jack o’lantern