J3-Golem

J3-Golem is the final boss of the planet Jupiter. He can be found on Themisto. He has a possibility of dropping one of the following on death: Volt Helmet, Volt Chassis and Volt Systems blueprints and Neural Sensors. He has also been known to drop 2x mods.

Appearance and abilities
The J3-Golem resembles an Ancient Disruptor, but his behavior differs completely from other Infested. Instead of a charge attack like other Ancients, the Golem instead uses a pull attack similar to the Pull ability of Mag when a player gets in range. This will pull the player right to him and allow him to either melee with claws or release a cloud of miasma around his body to deal poison damage. As for ranged attacks, the Golem can also toss grenades that explode into toxic fumes, dealing poison damage on hit or if the player walks into the fumes.

While the Golem has no shields, he makes up for this by having a decently large amount of health. All poison damage inflicted by him ignores shields and damage health directly, just like Toxic Ancients and Noxious Crawlers.

Strategy
Due to the Golem's poison-based attacks, extra caution is required to avoid having your health drained rapidly. While his grenade spam is already dangerous on its own, the most annoying and threatening of his abilities is Pull, which can yank you out of cover into the open and also put you in range of his poison cloud attack. As such, using long-range-high-damage weapons such as the Snipetron or the Lex are advised, so you can shoot him while staying out of his Pull's activation range. Staying far away from him (40 meters or more, the grenade reaches 30 meters on flat ground) will also make his grenades miss all the time, making other infested the only worry through the fight.

The Golem is best fought while standing behind short obstacles approximately up to your waist. As the Golem aims its grenades directly at your feet, they will impact the obstacle and leave you unharmed, while you can freely shoot at him. Even if he walks close enough, the obstacle will also prevent you from being pulled out.

When playing this map solo, an effective method is to kite the Golem to one end of the top walkway, then run to the opposide end and climb onto the red crates. He moves so slowly that you can take your time shooting his legs. Once he gets to roughly 30m away, jump down to the ground floor and run over to the other end of the top walkway then climb onto the crates again. He will regenerate a bit of his health when you do this, but it is fairly negligible.

Excalibur's Slash Dash ability is excellent for making a quick escape after being pulled.

With Mag, using her Crush ability will disable J3-Golem, breaking his legs and disabling his movement almost completely. He then can only use his Poisonous Gas and Pull abilities.

Trivia

 * J3-Golem is the first Infested boss, and was the only Infested boss before Update 6, which added Phorid.
 * The Golem is the only boss that doesn't seem to have a unique appearance.
 * J3-Golem is supposedly centuries old, which would probably make him the oldest boss in the game lore-wise.
 * It is said that J3-Golem was first created by the Orokins themselves as a super weapon in an ancient war against "the Sentients".
 * The Golem is renamed as Ancient Infestoid if encountered in an Alert mission.