You can't kill him or interact with him in any way, but there he is. In Wings of Liberty, during the fiery Devil's Playground mission head to the bottom right of the map to find Diablo.

The cheat should take effect immediately, and you're now ready to enjoy your playthrough. Type one of the cheats below to activate it, and look out for the chat log to display the word CHEAT in capital letters. To get started, launch a singleplayer campaign and press Enter on your keyboard to open the speech box. It's quick and easy to begin using these StarCraft 2 cheats.

Continued play after defeat: NeverGiveUpNeverSurrender.Disable victory conditions for continued play: TyuHasLeftTheGame.Disable cooldowns on spells: HanShotFirst.Enable fast builds and fast upgrades: CatFoodForPrawnGuns.Upgrade weapons, armor, and shields by a level: IAmIronMan.Gain 5000 of each resource: WhoRunBartertown.Disable the need for supplies: Bunker55AliveInside.Instant defeat: LetsJustBugOutAndCallItEven.