The Proving Grounds is the final level of the Swampy Pit, an optional dungeon located in the Flayer Jungle. It is home to the boss Death Projector, which must be killed as part of Level Challenge 2. The portal to Genesis can be opened from here by breaking the Zakarum Figure.
The Swampy Pit serves as testing grounds for Mephisto's latest siege weapon. The Death Projector slowly rotates, firing a devastating energy beam in a full circle, annihilating anything in its path.