Mayhem Mode is a game mode introduced in Borderlands 3. Mayhem Mode is activated upon the completion of the main story of the game.
Players are taken to a mysterious terminal aboard Sanctuary III that can enable four difficulty levels, from one through four(previously three). Taking on one of these Mayhem Modes ups the ante on risks and rewards across all worlds: enemies get increased health, shields, and armor, while you get bonus cash, Eridium, experience gains, and chances for better loot.
Mayhem Mode applies Mayhem Mods to any planet you visit, which force you to adapt to new playstyles and combat approaches in response to a random selection of modifiers. Modifiers for the current map may be viewed through the map screen.