Hunter Chopper

Background
The Hunter Chopper is an artificial boss mob crafted by the player in the Assembly Machine. It spawns as soon as it is placed down, like a spawn egg, and will immediately attempt to gun down any mob it finds, including you. Its only purpose is to drop scrap CMB steel for Gerald, other than that, it drops no XP or any other useful items. When finally killed, it explodes causing moderate terrain damage.

Creation
The Hunter Chopper is artificially constructed, it does not spawn naturally anywhere. It is primarily made of CMB steel, making it quite tough to make. It also uses expensive Fusionary Watz Plant calculation matrices for its onboard computer systems and presumed AI.

Dangers
The Hunter Chopper is automatically hostile to all mobs and players and will start attacking as soon as it reaches optimal altitude, if not instantly. It has an approximate health of 750 and very good resistance to damage.

It uses an "Emplacement Gun" that you gave it for its primary mean of attack. It is an automatic gun of some kind that does not run out of ammunition. It hits fast and it can kill mobs very quickly.

It also occasionally drops concussion bombs (bombs that don't cause block damage) in groups of 5, usually when it is directly above a mob/player or in a scenario when its Emplacement Gun cannot be used effectively.

Uses/Farming
The only purpose of the Hunter Chopper is to acquire a warped piece of CMB steel for Gerald. Excess CMB scrap can be smelted back into CMB steel ingots.

You cannot use it for your own purposes directly, unfortunately (such as flying it or making it attack/protect certain players/mobs), but you can technically plant it in an enemy location and force them to kill it or relocate.

How to Bring it Down
The Hunter Chopper is highly resistant to conventional weapons, even some low-level turrets, and nuclear weapons.

It will attempt to evade slow-moving projectiles such as mini-nukes and Heavy Turret Shells.

If you have no ranged instant-kill weapons, you will be forced to use heavy anti-aircraft weapons.

The best method is to use the WIP Turret, which is a heavy anti-aircraft gun, it can take down a Hunter Chopper in ~2 well-placed hits, however, the AAA shell it uses causes heavy block damage, meaning it could destroy friendly structures or itself by accident. Stinger rockets are the next best thing to use, they do minor terrain damage and are guided so the Hunter Chopper cannot evade it. Turrets are slower, but can still work.

Trivia

 * The Hunter Chopper has been in the mod long before Gerald or even satellites have been added.
 * When taking damage, it will occasionally drop items, usually CMB scrap or plates, as well as 4000K superconductors.
 * It is based on a very similar craft from Half-Life 2.
 * Extra points if you are getting chased down by it while you're on a boat.