Collect the Horseless Headless Horsemann's Haunted Metal.
Upgrade 50 buildings built by other team members.
Smash an enemy player's head in with your guitar.
Kill an enemy Heavy and take his Sandvich.
Kill a Spy who just backstabbed a teammate.
Jarate an enemy and the Medic healing him.
Jarate an enemy that you're dominating.
Have a dispenser heal 3 teammates at the same time.
Kill an enemy Spy that you have been healing.
Achieve 17 of the achievements in the Spy pack.
Win a round with at least 5 teammates on the elevator.
In a single life, kill an enemy while you are on the ground, in the air, and in the water.