HAN-D

How to unlock: HAN-D, also known as the "robot janitor", is found in the final level of the game, Contact Light. He has a chance to spawn in the cargo bay. Inside the bay, he is located in a foreground large obstacle crate, with its door slightly ajar. Inspecting the crate will open the door completely, revealing a deactivated HAN-D inside.

In the ending cutscene, the HAN-D specific text says: "..and so it left, servos pulsing with new life"

Tactics

 * Drones can auto target enemies. You don't need direct visibility. Keep in mind that you can only have up to ten drones at any moment, so try to use them only in an emergency for immediate healing.
 * While HAN-D doesn't have the ability to dodge or block, the drones are capable of healing. Try to save at least two just in case you need a sudden chunk of health restored.
 * When not doing a solo run, forced reassembly can stun a large crowd of monsters, allowing others to deal massive damage to a confined area. Mastering your timing on this skill can give you a good crowd controlling method.
 * It is important to acquire items that increase mobility and attack speed to make up for your crippling lack in both categories without the benefit of Overclock.  War banners are extremely effective, providing a buff to your already high attack stat and also giving you a significant boost in attack speed.