Argos, Planetary Core

Argos, Planetary Core is a massive Vex Hydra that was found trapped within the Leviathan's core. It is a unique Axis Mind whose size is comparable to Panoptes, Infinite Mind, and is the final boss of the Leviathan, Eater of Worlds Raid Lair.

Overview
While Leviathan consumes chunks of Nessus to convert into Royal Wine for the emperor, the titular Planetary Core was sucked into the Leviathan's belly alongside squadrons of Vex, to which the Vex Mind generated a massive barrier surrounding it and the nearby debris from the planet. Argos' barrier quickly began to clog up the Leviathan's massive vacuum and stalled its engine.

Meanwhile, a curious fireteam of Guardians stumbled their way aboard the Leviathan where they decided to branch off their natural surroundings to navigate the massive engine beneath it. Taking notice of the group of Guardians within the ship engine, Emperor Calus calls off his Loyalists and invites them to destroy the fearsome Vex mind. The raid team makes their way into the belly of the beast, where they exposed Argos from its outer casing using the cranium weapons leftover by its Vex brethren. Argos' destruction would caused its barrier to dissipate and the ship's engine threatening to consume the surrounding debris, including the Guardians. Calus would intervene and transmat them to safety, whereafter he would reward them for their tenacity in ridding his ship of the Vex.

Gameplay
Argos' encounter is structured very similarly to Aksis, Archon Prime and is split in two sections.

Break the Barrier
Initially, there will be a giant prism structure floating in the center of the triangular map; it will be protected by a barrier that will need to be brought down by shooting its Arc, Solar, and Void crystals. These crystals can only be destroyed with its respective Vex elemental cranium weapon, which must be obtained by fully charging its altar using Vex Cranium fragments scattered around the map. These fragments need to be inserted into one of the corners of the altar, and the elemental cranium weapon will appear when all the altar's corners have a Cranium fragment in them. This process is up against two impediments: masses of lesser Vex units and the triggering of Quantum Mines. If it takes too long to destroy a crystal, then the mines will arm themselves and eventually detonate, wiping the entire team. Successfully destroying all the crystals breaks the first layer of the barrier, finally revealing Argos, Planetary Core.

Destroy Argos
With its full form finally revealed, Argos begins to attack with its Aeon Maul, which has greater range and rate of fire than those wielded by normal Hydras. It will be protected by a prismatic barrier that can only be disabled by bringing the floating elemental charges on the top, left, and right corners in line with a switch at the center, again using the respective cranium weapons, which will be obtained in the same manner as last time. When the barrier is shut down, Guardians will gain the "Unstable Energy Boost" buff and be able to freely damage Argos. However, they must remain alert, as Argos will activate one of two self-defense protocols. It can fire a detainment prism from its eye, trapping anyone that it touches and sending them away from the main platforms, eventually killing them via Force Cage. Additionally, it will send a barrage of Supplicant missiles, which will seek their targets out and blast them apart. After a short while, the prismatic barrier will re-calibrate itself and fully shield Argos once again. However, it will occasionally bring down the barrier and attempt to rip the air with Void energy, signaling the charge-up of its Gravity Smasher bomb. If left to detonate on its own, it will instantly kill the whole team. The only way to shut this process down is to, from the surrounding semicircular platforms, destroy a pair of weak points that will be open: one on its middle segment arms, one on its head, and one on its back. Destroying any given pair of weak spots will briefly stun Argos, allowing some damage to be dealt, but it is recommended to get back to gathering craniums to initiate the damage phase again.

Prestige Mode Changes
TBA

You have to play with a set loadout of weapon types, e.g. Kinetic Pulse Rifle, Energy SMG, Power Grenade Launcher. Ammo reserves are disabled. You start with only a full Kinetic magazine and as soon as you empty it, the Energy Magazine is refilled, after that the Power Magazine. Sometimes it may refill two Magazines, and it will only cycle on as soon as every magazine has been emptied. Additionally, ammo drops are limited to rare drops of Heavy Ammo.

Quantum Mines now take 25 charges before being destroyed.

Enemies in general are harder to kill and deal more damage.

Trivia

 * The two main Vex Minds seen in the Curse of Osiris expansion, Argos and Panoptes, are named after the same character of Greek mythology. Argos Panoptes (also transliterated as "Argus") was a many-eyed giant who worked as a guardian and spy for the Olympian gods due to his ability to see everything at any time.
 * Argos is the largest Hydra ever encountered by Guardian forces, easily among the largest Axis Minds.
 * Argos is the third largest Raid boss, behind Oryx, the Taken King, and Riven.
 * It is unknown if Argos was the core of Nessus, or the core of a Vex world previously consumed by the Leviathan. If it hailed from Nessus, then its destruction likely stopped or at least temporarily halted the conversion of Nessus.
 * Argos is one of few raid bosses that has multiple encounters. Among them being Aksis, Archon Prime, Vosik, the Archpriest, Insurrection Prime, Kell's Scourge and Consecrated Mind, Sol Inherent.

List of appearances

 * Destiny 2
 * Curse of Osiris