“The Cow level is a lie,” taunts the in-game hint on a loading screen in Diablo 3, the-cake-is-a-lie-style.
That line is a lie.
The legendary cow level, famous in Diablo 2, is a novelty, something funny and something useful in the game. It had fairly good drop rates, and there was a chance to get an exclusive cow set. This was done by clearing all Acts in a given difficulty, grabbing Wirt’s Leg from Tristram, and then fusing it with a Town of Scroll Portal book in the Horadric Cube. The level had great monster density so it was a popular farming spot sometimes.