DRONE will auto target the nearest enemy. 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. Note: HAN-D's drones will be reset to 0 on entering a new level.
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. Since this ability has a wind up time is recommended to jump in the air before using it.
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. Warbanners are extremely effective, providing a buff to your already high attack stat and also giving you a significant boost in attack speed.
Unlike other melee-focused classes, HAN-D, at base fire rate, can't stun-lock enemies using only its standard attack, thus making items that boost the attack speed stat like the Soldier's Syringe exceptionally valuable.
When on a ledge and attacking enemies below, note that FORCED_REASSEMBLY can knock enemies up and onto your level.
A very effective and also very fun playstyle with HAN-D will require maxed Attack Speed (8 Soldier's Syringes), at least 2 Alien Heads, and any amount of Wicked Rings above 2 and 100% crit. With this combination of items you are able to simply hold down both HURT and OVERCLOCK gaining infinite boosted attack speed, attacking even faster than the Commando's Suppressive Fire. Though unless you have luck on your side, this is only achievable with the command artifact and major farming.
You can duplicate DRONES by killing enemies while in a run with more than one HAN-D. This gives DRONE to each of them thus combining them with Ceremonial Dagger and Glass Artifact makes every run extremely easy to complete.