Defend your house with traps

You have recently found a house off in the woods, off the path less traveled. It's a three story house, and for some reason they have a tower with a spiral stair case. They people who lived here are long gone, but they seemed have had several odd hobbies. There is a collection of ammo of all sorts in the master bedroom. They have a safe that weighs quite a bit. And the kitchen has uncountable amounts of knives and razors. There are several pulley systems in the garage, amongst other tools- such as two lawn lowers, five weed whackers, and a single chainsaw. The houses tower has a telescope with quite a long range of sight. You were listing to you hand held radio today and heard that a huge hoard was on the way- about two days off. The town below will keep them occupied for a while, so you have four days to set up traps for your home. You would like to hold on to this house for a while, so you will try to defend it. Don't worry, you have a zipline on the tower leading to a tree across the river, about 100 yards away. But that's a last resort, and this house has enough food and ammo to last you for three years-more if you ration out the food between you and the other three members of your group. You have four days to set up your home made traps- what will you defend your home with?