The Devil is native to the Kill Devil game mode. They are the only source of points in the game mode and to get those points a player has to kill the Devil before they blow up. If a Devil is not destroyed in the course of 3 seconds then it will plop down and explode, hurting everyone around it.
It takes 15 Devils for a team to win the game.
Devil explosions will sometimes go through walls.
You will do more damage if you hit the target
If killed by the Devil, it will not be counted as a death nor will it affect your KDR.