Raid Mode is a separate, arcade-style game mode that allows players to tackle various missions, either solo or with a co-op partner. In Raid Mode, you choose a character, equip weapons and custom parts, and then fight through waves of enemies in modified versions of the main story's environments. The goal is to clear the stage, defeat all enemies, and reach the exit. Completing missions earns you experience points, Battle Points (BP), and new weapons/custom parts.
Raid Mode features its own progression system, allowing you to level up your chosen characters, unlock new abilities, and acquire increasingly powerful gear. There are multiple difficulty levels for each stage, offering greater rewards but also posing a significant challenge. This mode is excellent for grinding for better weapons and custom parts, and for practicing your combat skills without the pressure of the main story's resource management.