The Grustrag Three

"Arrogant. Sadistic. Unstable. They are perfect for this."

- Councilor Vay Hek

 The Grustrag Three (commonly abbreviated as the G3) are a group of Assassins, founded by Councilor Vay Hek, who come after Tenno that have completed five consecutive Invasion missions against the Grineer. The Grustrag Three were formerly regular Grineer marines who (while aboard a troop transport) suddenly slaughtered their comrades, claiming that they were growing "impatient for the killing". After being committed to the Grustrag Reconditioning Facility, Facility Director Dr. Tengus discovered that the marines suffer from a rare mutation brought about by cloning, vastly increasing their combat potential at the cost of deteriorating mental faculties.

Under Vay Hek's order, Tengus reconditioned them, with the intent of focusing their aggression towards the Tenno instead. Although mostly successful, the Three still had lingering violent behavior towards fellow Grineer. To counteract this, Tengus developed the Grustrag Bolt, a device that limited their effectiveness against other Grineer personnel. Tengus had additional Bolts created, to be used against the Tenno during the Three's operations.

With The Grustrag Three now prepared for combat, Vay Hek deployed them with the sole purpose of attacking those who supported enemies of the Grineer. However, Sargas Ruk criticized Hek's actions, reminding Hek of the soldiers The Three have killed and warning him that they would eventually grow out of his control.

Leekter= Each marine is accompanied by a Carabus Sentinel, which are equipped with Laser Rifles to provide additional firepower. They do not have a name in game, only a health/shields bar, similar to Loki's Decoy.
 * -|Shik Tal=
 * -|Vem Tabook=
 * -|Carabus Sentinel=

When a player is defeated by the Grustrag Three, one of the three sentinels will detach from its host, then hover and deploy a shield over the downed player. It prevents other teammates from reviving the player while the sentinel attaches the Grustrag Bolt.

It also exists as an alternative skin for Dethcube, which is available for purchase for.

In General
Despite their bulky appearance, each member of the Grustrag Three is capable of a quick dash in any direction, which they use to avoid fire and close in on their targets. The Grustrag Three usually attack in turns, making it difficult to focus on a specific marine to take down.

Unlike the Stalker, the Grustrag Three are fully vulnerable to Status Effects and most Warframe abilities. As such, they can be easily incapacitated with weapons such as the slam attacks of Jat Kittag or the Fragor. Due to their weakness to status effects,  and  damage work particularly well on them, reducing their overall durability by a significant amount. damage can also be used, as it deals extra damage to their Alloy Armor on top of confusing them, potentially making them attack each other or fellow Grineer. However, their Carabus Sentinels cannot be damaged by any means, they are only destroyed if its respective marine is killed.

A strong Specter can greatly assist players in combat, either to provide additional damage or to draw attention away from players.

Utilizing Warframe Abilities
They are vulnerable to most abilities, especially abilities that induces ragdoll or stunlock such as Hydroid's Tentacle Swarm, Nekros's Soul Punch, Mag's Pull and Zephyr's Dive Bomb works fine against them. Nyx's Pacifying Bolts can stun them for an extended amount of time. It is important to note however that their Carabus Sentinels will still attack players regardless if the Three are on their feet or not.

The blinding effects of Excalibur's Radial Blind and Mirage's Prism can also be used to incapacitate them, albeit with a shorter duration. They can also be distracted by Loki's Decoy and Saryn's Molt. Nova's Molecular Prime can slow them down and allow players to deal additional damage on them.

Oberon is a good choice to use against the Three, as almost all his abilities deal  damage on top of Smite and Reckoning having guaranteed chances to inflict confusion on them.

Trinity can indefinitely keep two of the Three stunned at the same time by chaining Well Of Life and Energy Vampire or focus on killing a single member by casting Energy Vampire on the same target as Well Of Life is about to expire as the damage ticks created by Energy Vampire are calculated based on the target's current health. Since Well Of Life increases the target's health pool for the duration of the ability, this causes Energy Vampire's damage ticks to deal very high amounts of damage if this combo is performed correctly.

Loki and Ash can respectively use Invisibility and Smoke Screen to cloak themselves and attack the Three safely. Valkyr's Hysteria works well against the Three, provided Valkyr has Rage, a fully-ranked Vitality and/or Steel Fiber to improve her energy regeneration and durability. Bear in mind that this "head-on" strategy runs the risk of killing/destroying any Companion you might have with you and poor timing can also leave you vulnerable as well, so exercise caution if you want to survive the fight.

Not all Warframe abilities have an effect on the Grustrag Three; Vauban's Vortex or Zephyr's Tornado cannot be used to hold them down and Nekros' Terrify will only reduce their armor. Loki's Radial Disarm will treat them like Infested, knocking them down and dealing damage instead of stripping them of their weapons. Nyx's Mind Control and Chaos will also not affect them.

Certain Warframe abilities have reduced effectiveness towards the Grustrag Three; duration-based crowd-control ability such as Rhino's Rhino Stomp, Mirage's Prism, Excalibur's Radial Blind are less effective, cutting their duration by 50% or 75%, as observed. (needs confirmation)

Arrival
Triggering an attack from the Grustrag Three requires the player to have a death-mark. This is acquired by supporting the Corpus in at least five instances of Invasion missions. Death marks are acquired separately for each invasion mission which requires you to fight for the corpus on Grineer offensive invasions at least five times in a row. Once the death-mark is acquired, the player will receive a message from Vay Hek, stating: Acquiring another death mark will trigger this message: Similar to the Zanuka Hunter, the chance The Three will appear on any given Grineer Mission is additively increased with each player in the party with a death-mark.
 * "Interfering with our operations is unacceptable. You will be shown your place. Your punishment has been ordered."
 * "You continue to assist our enemies. Your meddling will NOT be tolerated."

They have a chance of spawning once every 10 seconds for the first 5 minutes.

Before they appear, the Lotus will try to warn you (with her transmissions distorted), and eventually pleads you to abort the mission (ignoring the mission's original objective in the process). As of the most recent update, this can even mean ignoring an entirely uncompleted objective, such as Mobile Defense.

Each marine has a chance to drop Neurodes, a component/blueprint for the Brakk, a rare mod (such as Natural Talent), or a rare Fusion Core upon defeat. If The Three are successfully defeated, players may opt to head to extraction without completing the original objective.

Defeat
If the Grustrag Three manage to defeat the player, the session will automatically fail, taking the player back to the main menu. A new inbox message from the Lotus will then appear stating that The Grustrag Three have attached a Grustrag Bolt to the player's Warframe, crippling its powers when attempting to fight them. As long as the bolt is attached, it will lower that frame's damage against Grineer by 50%. Attached to the same message will be a Bolt Release blueprint to release the Grustrag Bolt.

Tips

 * It is possible to destroy the Carabus Sentinels of the G3 to prevent the bolts from being applied, it will instead abruptly end the defeat with a death.
 * The Grustrag Three's corpses can be Desecrated to improve your chances of getting Brakk components, and their corpses can also be dismembered with slash weaponry prior to being Desecrated to increase the chances of getting Brakk components or other loot.
 * Grineer proxies will still consider the Grustrag Three hostile, though the opposite is not true. Do note, however, that their targeting prioritizes Tenno over the G3, and as such, players wishing to exploit this must remain hidden from sight, either by cloaking or by hiding behind terrain.
 * Since the Grustrag Three's drops remain the same in The Law of Retribution trial, it is possible to obtain the Brakk and Grustrag Three Sigil without the use of death marks. It is also worth mentioning that the Grustrag Three will NOT drop anything during the quest A Man of Few Words nor during the Weekly quest unlocked afterwards.
 * The Grustrag Three are fully affected by Naramon's Focus ability, Mind Spike.

Trivia

 * They are the first death mark enemy that consist of multiple entities. The Stalker and The Zanuka Hunter only consist of a single entity.
 * Upon spawning all players are contacted by the Lotus. However only one player will have his mark consumed.
 * When spawning, all the players will be taunted, but then one player will be taunted mentioning his name and Warframe. This player will have his mark consumed and must do three invasion missions for the Corpus to regain it.
 * At the time of their introduction, The Three were guaranteed to drop a mod, a Brakk component, and Neurodes all at once upon defeat, potentially giving players all the Brakk components in a single encounter. This has since been patched.
 * The Grustrag Three appear to have some heavy duty jamming technology somewhere on their persons, preventing the Lotus from properly warning any targeted Tenno, keeping her in the dark as much as possible from what is happening.
 * The Grustrag Three currently have the same drop table, differing only in Brakk components.
 * The Grustrag Three seem to have similar armor components to those of Lieutenant Lech Kril. Although, this armor similarity could possibly imply a category of those for Grineer Commandos, an even higher tier of Grineer troops than those of the Elite Lancers or the Napalms.
 * Their body meshes share arm and leg geometry with Lieutenant Lech Kril. The jarring quality difference is a giveaway.
 * Although Leekter wields a Manticore in battle, his codex entry used to depict him using a Brokk instead. This has been fixed for.
 * According to Shik Tal's Codex entry, the Grustrag Three have apparently cost Ruk an entire battalion of Grineer troops, which Ruk views as incredibly valuable to him, and has stated he'd kill the Three on the spot for their treason, if given the chance.
 * Like the Stalker and the Zanuka Hunter, they have their own soundtrack.
 * It is also used by Syndicate Death Squads.
 * Like Vor, Alad V, and Ruk, Shik Tal is voiced by [DE]Skree. It is currently unknown who voices Leekter and Vem Tabook.
 * Doing the same invasions after playing it three times can increase the spawn chance of the G3. Although it is not the most well-rounded way to spend time, it can help to grind Brakk parts.
 * If G3's intended target is captured, the mission will fail even if there are squad members alive and uncaptured remaining. There are cases in which this will not work properly.
 * The text on the Grustrag bolt, when translated, reads "PROPERTY OF GRINEER".
 * Their name may be a reference to the "G3", a musical project leaded by Joe Satriani involving himself and two other famous guitarists that change every year

Bugs

 * The Grustrag Three appearing in a Survival mission can prevent the five minute interval rewards from being given for the rest of the mission.
 * A similar bug can occur during interception missions if the broadcast reaches 100% while you are fighting them. The screen that allows you to continue the fight or end the mission no longer appears and Lotus assumes that you wish to continue to fight, making the mission impossible to complete.
 * Being healed by a health restore or an ally's ability whilst simultaneously being downed may leave players in a constant loop of being downed, and also unable to be revived.
 * It's possible for The Grustrag Three to spawn in areas that are no longer reachable, such as taking an elevator before starting defense or interception which becomes inoperable. This will cause them to die instantly and their drops unobtainable.