Smoke bombs are bombs that explode to cause minor damage and cause a billowing cloud of smoke to fill the room that they exploded in. The smoke lowers the perception of everybody in the room, making it harder to spot people hiding, backstabbing, ambushing and inhuming (or doing anything while hidden). The smoke will remain in the room for a period of time, and anybody entering the room will be immediately affected by it.
The ball itself is created in a pottery room by forming a hollow ball. A fuse must be added to this, with the number of inches left out relating to the number of seconds until the bomb explodes after it has been lit.