The Proving Grounds are special challenge arenas found throughout the world. Each Proving Ground is tied to a specific weapon and offers a unique challenge designed to test your mastery of that weapon. Completing a Proving Ground rewards you with a special upgrade for the associated weapon, often a powerful one.
To access a Proving Ground, you must first find its entrance in one of the main story levels. Once found, you can return to it at any time from the Skyway. Challenges range from defeating waves of enemies within a time limit to navigating obstacle courses using only that weapon's abilities. Experiment with different weapon upgrades and Secret Skills to find the most effective strategy for each challenge.