When you are alive you can trade people who are dead. It shows you all the dead people in the offer trade box even if the haven't been IDed.
EDIT: also igniting someone and then them spectating someone causes the person they are spectating to catch on fire. Also igniting a person in spectator mode allows them to fly around the map as a ball of fire.
EDIT: also igniting someone and then them spectating someone causes the person they are spectating to catch on fire. Also igniting a person in spectator mode allows them to fly around the map as a ball of fire.