Stealth

When Warframes are not detected by enemies, they are in stealth, able to sneak past combat encounters or perform devastating attacks to unsuspecting targets. However, conspicuous activity will raise the alertness of observant enemies, which can increase the difficulty of the mission. At various levels of alert, enemies may become more careful, call for help from other nearby enemies, or trigger the alarm control panels to summon backup from other rooms. Alertness decreases over time.

While most missions in WARFRAME do not require or explicitly reward stealthy play styles, the game provides an assortment of weapons, mods, and a different damage multiplier that enable an alternative game play for advanced players who seek immersion or challenges.

Alertness
Not to be confused with the mission type, Alert.

Enemies can only see things in a short, frontal cone and their view can be further restricted by the environment. They are bad at noticing threats at a distance or anyone somewhat above their heads. Crouching will hide a Warframe's silhouette well, and being cloaked (invisible) allows the Warframe to move past enemy eyesight without triggering any suspicion. Loud noise, however, can cause enemies to fire towards invisible Tenno–shooting most weapons while visually shrouded will still alert nearby enemies from all directions.

Distant gunfire or suspicious activity (noticing the corpse of an ally, for instance) may temporarily put enemies in nearby map tiles into a minor alert. These enemies keep watch from behind cover or patrol with guns raised and are more sensitive to the Tenno presence. As they don't know exactly where their threats are, they are more cautious, looking down corners and expanding their vision. This can usually be heard by the player, as enemies talk to each other while in this state. From this state and above, enemies can no longer be Stealth Attacked until their alertness level lowers below a minor alert.

Enemies in a tile enter full combat alert when they see or hear the Tenno directly. In this state, they will attempt to pursue the Tenno while getting backup by summoning nearby allies or activating alarms via control consoles. Enemies from other tiles will not enter this state if the enemy that detects you is killed quickly enough and the alarms are not triggered. Additionally, their range of vision expands and they will be able to spot Tenno and their companions from far away, even after the player disengages from combat. Note that backup troops arriving in nearby rooms may not know what the threat is, and will be put into minor alert instead. Players can infer an ongoing full combat alert from how enemies will notice and fire upon the player from much further away than before.

Infested and Corrupted enemies are exceptions because of their hivemindedness. They will not use manually activated alarms, but once even one unit reaches full combat alert every other unit in a huge range will enter minor alert too. And, since there are no alarms, it is not possible to remove alerted states. New enemies may still spawn unalerted though, and minor alerts work as usual.

The minimap will change color depending on the alertness of the room's occupants with White, Amber, and Red referring to enemies being unalerted, in a minor alert, or a full combat alert respectively.

Control Panels
Control consoles are liberally scattered around most tilesets. If activated by an enemy, it will alert the entire room and may spread the alert to the whole map. Killing the enemy before they finish using a control panel (they take about 1.5s to complete the alert) will prevent the alarm from sounding. Enemies will not consecutively run up to the same console to set off the alarm, but if the fight takes long enough, another enemy will likely attempt it. Note that if the enemy activating the alarm takes enough damage, they will abort activating the alarm and turn to attack the Tenno. If an alarm is set off, the alarm can be reset by going to another control terminal and hacking it without further spread of notice. While it is possible for stealth to be recovered in missions populated by the Grineer and Corpus, the Corrupted and Infested factions do not use control consoles to sound alarms and any open combat will result in these factions' enemies becoming permanently alert for the rest of the mission.

Even when the control panel has been accessed and an alarm has sounded, enemies will lose track of the Tenno when the last group of enemies killed is not close enough to set the next group of enemies on alert. They will wander as if they never heard an alarm and it is possible to finish a Stealth challenge reward this way. By sprinting through rooms quickly, one can sometimes avoid alarms being set off or escape to new rooms distant enough from the hostile room arming its alarm that these new enemies won't hear it. Equipping a sprint speed mod on the Warframe can increase this chance of escape.

Security Cameras and Turrets
Cameras can detect Tenno and deploy any nearby Corpus Turrets to engage in combat. However, triggering a camera or shooting a turret will not trigger any kinds of alertness for other enemies, nor will the general alarm state in the mission cause the security cameras to be alerted. The challenge reward for 10 stealth kills can easily be accomplished in high-alarm scenarios by destroying cameras that haven't personally witnessed the player. The turret, on the other hand, is hard to destroy if never activated but note that its shots are silent and do not alert the enemies in nearby rooms.

Stealth Damage Bonus
Standard melee attacks are affected by a 700% stealth damage bonus when attacking unalerted enemies, or when cloaked by an ability (e.g. Invisibility). This damage increase changes the color of regular damage pop-ups from white to yellow (similar to critical hits).

Enemies are not always susceptible to increased melee damage for every melee attack. If the player comes into physical contact with an enemy while attacking it, the damage bonus will be temporarily removed. Attacking from different angles and giving the enemy some distance will help improve the consistency of the attack damage. As long as you are invisible, the 8.0x bonus will reset every 2 seconds after an interaction with an enemy (Shooting, melee attack, physical contact).

The Stealth Damage Bonus is affected by the rank of the weapon. As mentioned above Rank 30 weapons deal 700% bonus, while unranked ones only gain 100%. Inbetween that the bonus scales linearly as per the formula:

Stealth damage bonus may also apply to enemies that are made vulnerable to Finisher Attacks, as example Excalibur's Radial Blind. For a full list of options please check here.

Critical hits while under these effects will still appear yellow or in their respective color for higher crit tiers. The damage bonus from crits and stealth stack additively with each other.

Stealth Attack
As long as an enemy is unaware of the Tenno presence, a stealth attack may be executed on them. To perform a stealth attack, the player must approach an enemy from behind and activate the stealth attack prompt. Successfully performing a stealth attack will deal a massive amount of damage during a special animation, during which the Warframe is immune to damage and will not be attacked by enemies. The attack's final damage depends on the melee weapon type used, on top of the 8.0x melee damage multiplier described in the preceding section.

As these multipliers factor total weapon damage, equipped mods (including critical chance and critical damage mods) will also affect the stealth attack's final damage. Stealth attacks inflict True Damage, which is unaffected by armor. Damage value pop-ups always appear yellow, identical to critical hit damage values (even if the stealth attack did not crit).

A complete kill ensures your target cannot recuperate and bring attention to you. Performing an unsuccessful melee stealth kill (which happens often when in a high level area, or when stealth attacking heavily armored Grineer) or failing to kill an enemy with a silent ranged attack or ability will alert the enemy after a short moment. Due to that short moment, though, it is possible to execute consecutive stealth attacks by pressing melee key quickly right after previous stealth attack is finished. This is also noteworthy for eliminating pairs or groups of enemies, as enemies within 5 meters of the victim will become cautious (even without seeing the Warframe) for roughly 20 seconds due to the sound of their comrade's death.

Enemy Eligibility
Some enemies do not grant a stealth attack prompt. Many mechanical or robotic enemies are immune to stealth attacks, either completely or from specific weapon types.

Grineer
 * Roller

Corpus
 * Ospreys
 * Cameras
 * Turrets

Weapons you can however stealth attack a MOA with are: Sword, Machete, Staff, Polearm, Sword and Shield, Tonfa, Whip, Nunchaku, Blade and Whip, Dagger and Rapier. (most likely being expanded as time goes on)

Some Bosses, such as The Sergeant, can be stealth attacked. The damage done will usually not be sufficient enough to kill them in one hit. Non-humanoid Bosses such as Phorid and Jackal are immune to stealth attacks.

Special Warden enemies take bonus damage from stealth attacks, allowing a larger chance of instantly killing them, which is crucial in order to complete their host mission with the most points. This is especially useful since Wardens have very high health and will trigger the execution sequence if the player is spotted.

Affinity Bonus
Killing unaware enemies will trigger a Stealth Kill Affinity Bonus, which increases the amount of affinity that a player gains from killing said enemy. A notification appears in a player's HUD to the left of the shield counter upon performing a stealth kill, which will display the bonus affinity value for that kill, as well as the time remaining for the combo. The default bonus affinity value is 100%, which can be increased by performing a subsequent stealth attack within 30 seconds of the previous one, which will add another 100% to the bonus value, e.g. killing a second enemy stealthily will grant a 200% affinity multiplier, the third granting 300%, and so forth until it caps out at 500%, whereupon any successive stealth kills will provide said bonus as long as they are made within the time limit. Stealth kill affinity bonuses can be initiated using any attack as long as the enemy is unaware of the player's presence, though melee weapons grant twice the amount of stealth kill affinity compared to ranged weapons or abilities.

The stealth kill affinity bonus resets if the Warframe kills an alert enemy or is attacked by an alerted enemy (Companion, Sentinel, Operator do not reset the bonus). Only enemy units will trigger these affinity bonuses. Environmental objects like Corpus Turrets, Security Cameras, Sensor Bars, and Storage Containers will not reset the multiplier nor do they count as a stealth kill. Certain units like Sensor Regulators are also considered objects, and thus will not initiate stealth affinity bonuses.

Oddly enough, certain Warframe powers (like Paralysis) and Melee Combos that initiate stagger may initiate stealth kill affinity bonuses upon performing a Finisher, even if the enemy was previously aware of the player.

Fighting Silently
Using noisy weapons and abilities will alert enemies within 50m. Equipping max-rank, or  will render any pistols, rifles or shotguns completely silent.

Silent or Quiet Weapons
All melee weapon attacks are silent, including those from thrown weapons, the Deconstructor, and the shotgun attack of the Redeemer (as long as enemies are more than 5 meters away from the player when it is fired). The following ranged weapons are also innately silent or otherwise produce less noise than standard when fired:

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Silent Abilities
The following table lists the abilities which are either silent to enemies or enable the player to perform silent kills. Note that direct damage abilities (Shuriken, Slash Dash, etc.) are silent if cast while invisible or shrouded.

Tips

 * Be patient and learn the behavior of your enemies. Good timing means you can avoid patrols and position yourself to attack enemies from behind.
 * Check your surroundings to sneak up on an unsuspecting enemy without interruption. Do not eliminate an enemy if it is being watched by another enemy. If enemies see a corpse that has not disappeared yet, they might be alert for a short period of time.
 * In large rooms, look for exposed ceiling rafters or ventilation shafts that can be used to traverse areas without the risk of directly encountering enemy patrols.
 * Always allow at least a two-meter distance between enemies before engaging them in melee as a precautionary measure.
 * Staggered enemies don't make sounds, but they become alert and will alert others if given a chance to recover. If you did not kill an enemy with a single hit, keep it staggered by stealthy means and you'll be fine. procs will lengthen the amount of time an enemy stays staggered.
 * Stand to the side of a door to open it and peer slightly by moving the camera. You can see around the left edge of obstacles by changing the camera to hang over your left shoulder (default is ).
 * Beware of breakable reinforced glass, unless it is part of the player's tactic to cause a controlled lock down to eliminate all enemies inside a chamber. This action will not cause a high alert.
 * Having a Sentinel equipped may compromise stealth, as it does not hide behind low cover. If you do bring a Sentinel, make sure to remove their targeting precept mod or the weapon itself. The only exception is Shade's, which will not target enemies unless they are attacked players.
 * If you have a Shade with the ability, consider sprinting toward an enemy to activate it quickly.
 * Sniper Rifles and other long range weapons such as the Latron are less likely to attract attention. This is most likely because the weapon noise at the gun's barrel is far greater than the noise at the impact site.
 * Use a Codex Scanner or Synthesis Scanner. Scanners can show enemies within 50 meters through walls and behind cover. However, if used to scan, it will remove the scanned enemies from the player's view.
 * Practice stealth play on low-level Extermination missions. As players will usually one-shot almost all enemies, they will get the hang of silent weapons, the enemy's cone of vision, and other things that would be difficult to practice with the most difficult of missions.
 * Try doing stealth missions solo, as various players that may join mid-round may not agree with taking a stealthy approach to a mission. A solo player is also able to improve on their mistakes, and their mistakes alone.
 * If going invisible in Corpus stealth missions, be very careful of Nullifier Crewmen and Fog Combas and Scrambuses, as they can disable a Warframe's invisibility powers.
 * Unalerted enemies that are sent to sleep by Equinox's Rest and Ivara's Sleep Arrow can be killed using automatic weapons that deal weak damage per shot without alerting them, as long as the enemy is killed quickly enough after passing their waking damage threshold. Both abilities can also be used on clustered enemies to prevent them from being alerted by kills made in their proximity.
 * The fiery battle damage environmental hazard will spawn extremely alert enemies at the start. To resume stealth, kill all alert enemies in the area quickly and hack the nearest panel to reset the alarm. They will revert to an unalert state after some time. If the alarm is not reset, all enemies will spawn in alerted state.

Grievances
There are some flaws that have not been addressed.
 * With projectile-based weapons, (Primary, Secondary weapons, AND thrown melee kills) enemies will see the projectiles and become alert.
 * The practicality of attempting assassination on heavy and shielded units, especially purely mechanical enemies such as Corpus Ospreys.
 * If you aren't at the same altitude as the target, the prompt will not easily appear.
 * Being at a lower altitude will teleport the enemy to your current location, possibly causing them to overlap with walls. This usually happens on stairs.
 * A Prompt will appear and disappear unexpectedly when the enemy is alerted.
 * After each stealth attack, you finish standing up, which might reveal your position. You will need to release and re-press the crouch button to return to crouch position. If you are using a toggle crouch key, simply press it during the animation to return to crouching when the attack completes.
 * Dropping off a ledge will also cause you to stand upon landing.
 * A glitch can occur when stealth attacking Infested Ancients, Heavy Gunners or Corpus Techs. Upon entering the stealth attack animation, the enemy will shrink to roughly the player's size. (This shrinking glitch can also occur when using Ash's Blade Storm. Blade Storm has a possibility to also shrink Grineer soldiers, as well as a few bosses, including Lieutenant Lech Kril.)
 * It is possible to attempt a stealth finisher without a melee weapon. This uses the finisher animation of nikanas, but does very little damage.


 * For a long time, it was possible to notice enemy spawn points (usually in Survival missions) and continue to fire your weapon under stealth to gain continuous stealth bonus experience, allowing quick leveling and Focus affinity.
 * To counter this, a mechanic was introduced wherein newly spawned enemies have a hidden timer active. This timer, which can be around 4-8 seconds or in rare cases indefinitely, causes killing this otherwise unalerted enemy to not count as a stealth kill, and thus will reset any stealth bonus multiplier you have if this enemy is killed. This is why players may notice that despite all enemies being unaware of your presence, killing them all at once with an explosive weapon will often not give you any stealth affinity, or lose your current stealth multiplier.