Pumpkinhead

The story begins a long time ago, out in the country when a mother, and father try to protect their son from seeing what is about to happen. The relentless revenge demon, Pumpkin is perusing his victim. The man tries to get into the home but the father will not allow it. Pumpkinhead finishes what he started and the little boy, Ed Harley (Lance Henriksen) got out of bed to watch it all from his window. Now Ed is a grown man who has a young son. After six out of town kids arrive at Ed Harley's store, Pumkinhead's story is told by some local children. Shortly after,one of the six out of towners, Joel a criminal, starts to race his dirt bike. He jumps over a mound of dirt and hits Ed's young son. Because he is on probation and has been drinking, the punk gets his bike and flees the scene. He fights with his friends about going to get help and the little boy dies. When the father, Ed finds his dead son, he can think of nothing but revenge. His thoughts turn to the demon that he saw take revenge when he was a boy. He seeks the old witch that can conjure Pumpkinhead. Ed Harley follows her instructions and the huge, evil demon awakens. After Joel has taken his friends hostage to keep his wrong doings a secret, one of the girls, Maggie starts to lose her mind. She runs off and as Steve, Joel's younger brother tries to stop her. Pumpkinhead hides in the trees and strikes. As it rips Steve to shreds, Maggie runs back to the cabin for help. Joe and Jeff go looking for Steve with guns. Just then, the evil vengeance demon appears at the window. It hangs Steve's bloody body in front of the door, and as Maggie screams, Pumpkinhead grabs her and runs off. It soon returns and grabs another girl and chokes her in the top of a tree and then drops her onto a boulder and claims victim number three. The remaining three victims run looking for help. The hillbillies that live in that area know that if they help, Pumpkinhead will come for them as well. Ed Harley feels something awful every time his demon kills. He decides to help stop it and he meets the three remaining survivors. Soon, Pumpkinhead arrives and Joel and Harley unload their guns into the beast. Then, when they think it is dead, it rises and shoves Joel's rifle through his chest. Ed is bitten by a dog and Pumpkinhead feels the pain, but Ed did not notice it. Kim and Jeff run for their lives until a young hillbilly, Jimmy Joe decides to help them. Pumpkinhead pursues them through an old burned down church and grabs Jeff, wounding him badly. Wanting to stop this, Ed Harley drives around until he finds Kim and Jimmy Joe, and then takes them into his home. Soon the evil one appears, drops Jeff's body and enters the house. In a terrifying scene it goes for Jimmy Joe first. Then they all escape outside where Ed gets stuck by a pitch fork and sees that is hurting Pumpkinhead. Ed figures out that he can only kill the beast by killing himself. Jeff who is still alive, helps Kim buy some time. Just as the monster is about to kill jackass Ed shoots himself. But Ed Harley still lives. Kim shoots him and ends this forever and Pumpkinhead goes up in flames, never to be seen again. Well, until the old witch buried the remains back in it's resting place until the next time it is called upon.

Question: What does Ed realize will kill Pumpkinhead?
Answer: killing himself