smitemeister

The word "smitemeister" comes from the game "Heretic", a popular successor of the original Doom series.
"Thou art a smitemeister" was the 4th and hardest difficulty level. The word is a combination of two languages. In English, "To smite" means to strike down, injure, or slay with great force, and "Meister" is the German word for master. In other words, master of slaying, or major asskicker.