Sentinel

:Not to be confused with Sentient.
Sentinels are hovering companions that follow their Tenno masters around and assist in various ways, dependent on the precepts used to program them. It is possible to program sentinels with precepts, or skill mods, that can turn a sentinel into an attack drone or a support drone. Sentinels can also accommodate their own unique stat-increasing Mods, similar to Warframe mods. 
Sentinels, like Weapons and Warframes, level up with Affinity. They have health, shields, armor, a personal weapon, and energy reserves. They can be targeted separately from their Tenno master and do not go into bleedout; they will immediately explode and automatically revive after 60s, modified by Mods such as (Or for Djinn) and . Enemies tend to target a Warframe first, but may target the sentinel if it acquires threat.
Each Sentinel comes with a unique weapon, taking up a total of two Robotic slots, which are independent from Warframe and Weapon slots and shared with Robotic weapons and MOA Companions. An additional pair of slots costs to purchase. All Sentinels will come with two mods specific to their type. Sentinels have four Polarity slots, an Orokin Reactor upgrade slot, and can be Polarized with a Forma.
Currently, all Sentinels may be acquired and equipped regardless of Mastery Rank.
==Acquisition== 
*The blueprint for Taxon is awarded for completing the Earth to Venus Junction. Additional copies can be purchased from the Market for .
*The blueprints for , , , , and can be purchased from the Market for .
*The blueprints for and can be Researched from the Bio Lab and Energy Lab respectively in the Clan Dojo.
*The blueprint for can be purchased from the The Business on Fortuna for after reaching Rank 5 - Old Mate with Solaris United.
*A built can be purchased from Baro Ki'Teer for and . Note that Baro Ki'Teer's stock changes with each appearance, and this weapon may not be available on a succeeding appearance. It can be traded, but only for unranked copies without Forma or Orokin Reactor installed.
*The components and blueprints for are obtained from Points of Interest and Arva Vector Defense from Rotation B+C in Neptune Proxima missions, or through Trading between other players.
*The components and blueprints for , , , , , and are obtained through Void Relics, their respective Prime Access packages, or through Trading between other players.
Note that acquiring a Sentinel require two open Companion Slots: one for the Sentinel itself and one for the Robotic Weapon they come with.
==Robotic Weapons==
Sentinels can equip other Sentinels' weapons (with the exception of /'s /, which can only be equipped on Helios, though Helios can freely use other weapons) provided additional weapons are available. However, the only way to get another sentinel's weapon is to craft that particular sentinel to retrieve their specific weapon. All sentinels do not attack by default unless they possess an attacking precept such as . Players may also opt to unequip a Robotic weapon altogether if attacking enemies will be detrimental to the given mission. Though Robotic weapons can be sold independent of their parent Sentinel, the player cannot sell their last Robotic weapon.
Sentinels also share Robotic weapons with MOAs. Even though most Robotic weapons are acquired by building a Sentinel, Legs in Fortuna sells blueprints for the Robotic weapons , , , and , which are not attached to a Sentinel and can be used by both Sentinels and MOA Companions. The Hound weapons , , and can not be used by Sentinels.
All Robotic weapons can use normal weapon mods, provided the mod is compatible with the Robotic weapon in question (e.g. the 's can use Sniper Mods along with Rifle Mods, but the 's can only use Rifle mods). Most mods work as normal, including mods that affect Fire Rate, base damage, Multishot, Critical Hits, Elemental Damage, Magazine Size, Reload Speed and Status Chance. Mods that affect Ammo Maximum have no effect on Robotic weapon because they already have unlimited ammo reserves.
A weapon mod can be used in both a player's active weapon and their sentinel's active weapon. For example the can use the same copy of equipped on a .
Robotic weapons do not possess an Exilus slot and cannot equip Arcane Enhancements.
==Sentinel Mods==
Aside from the pool of mods shared between all Sentinels, there are at least two exclusive Sentinel Mods for each Sentinel (including any available variants) that modifies its behavior during combat. Typically, these are obtained as soon as the player claims them from the Foundry, though some of them can drop from enemies, and others can be found from other sources.
===Mod Priority===
As with all Companions, Precept mods will have different priorities in which they are used, based on which slot they equipped in; the top left mod slot has the highest priority and will be used most often, while the bottom right mod slot has the lowest priority and will be used least often. Managing these mods is key to get the most out of your Sentinel.
==Sentinel Stat Comparison==
<tabber>Base Stats=
Name	Base Health	Base Shields	Base Armor	Nominal Base EHP	EHP + Shields	Base Range	Polarities
 	560 	250 	80 	709.3 	959.3 	30 	
 	650 	300 	150 	975 	1275 	30 	
 	560 	250 	80 	709.3 	959.3 	30 	
 	600 	300 	150 	900 	1200 	30 	
 	700 	150 	80 	886.7 	1036.7 	30 	
 	560 	250 	80 	709.3 	959.3 	60 	
 	560 	250 	80 	709.3 	959.3 	10 	
 	700 	300 	100 	933.3 	1233.3 	10 	
 	560 	250 	80 	709.3 	959.3 	30 	
 	560 	350 	175 	886.8 	1236.7 	30 	
 	560 	250 	80 	709.3 	959.3 	30 	
 	600 	130 	80 	760 	890 	30 	
 	700 	300 	80 	886.7 	1186.7 	30 	
 	700 	300 	100 	933.3 	1233.3 	30 	
 	560 	250 	80 	709.3 	959.3 	30 	
 	560 	250 	80 	709.3 	959.3 	30 	
 	450 	600 	150 	675 	1275 	30 	
|-|Max Stats=
Name	Max Health	Max Shields	Max Armor	Nominal Max EHP	EHP + Shields	Max Range	Polarities
 	1960 	875 	280 	3789.3 	4664.3 	30 	
 	2275 	1050 	525 	6256.3 	7306.3 	30 	
 	1960 	875 	280 	3789.3 	4664.3 	30 	
 	2100 	1050 	525 	5775 	6825 	30 	
 	2450 	525 	280 	4736.7 	5261.7 	70 	
 	1960 	875 	280 	3789.3 	4664.3 	60 	
 	1960 	875 	280 	3789.3 	4664.3 	10 	
 	2450 	1050 	350 	5308.3 	6358.3 	10 	
 	1960 	875 	280 	3789.3 	4664.3 	30 	
 	1960 	875 	280 	3789.3 	4664.3 	30 	
 	2100 	455 	280 	4060 	4515 	30 	
 	2450 	1050 	280 	4736.7 	5786.7 	30 	
 	2450 	1050 	350 	5308.3 	6358.3 	30 	
 	1960 	875 	280 	3789.3 	4664.3 	30 	
 	1960 	875 	280 	3789.3 	4664.3 	30 	
 	1575 	2100 	525 	4331.3 	6431.3 	30 	
</tabber>Effective Health (EHP) calculated as
\text{Effective Health}=\text{Health}\times\frac{\text{Net Armor}+300}{300}, and does not account for damage type. 
Range refers to the attack range of that Sentinel's specific targeting precept.
==Comparison to Other Companions==
Advantages: 
*Easy to acquire — requires only blueprints and resources to build.
*Can engage enemies at range.
*Can instantly recharge its owner's shields when depleted.
*Can be equipped with different weapons.
*Tethered to the player, keeping it from getting caught up on terrain or engaging in combat unrelated to their owner.
*Wider array of crowd-control options.
*Weapon can apply status effects more consistently.
*Can use robotic-exclusive mods like .
Disadvantages:
*Comparatively fragile in combat. 
**Lower maximum shields overall.
**Lower maximum health.
**Cannot use , , or .
**On Incapacitation, the Sentinel will float beside their owner in a damaged state and cannot be manually revived.
*Requires the mod in order to attack, whereas other Companions will automatically attack without any associated mod.
*Consumes 2 inventory slots when retrieved from the Foundry, one for the Sentinel and one for its weapon.
*Are always within range of status effects on the player, chaining to them and often dealing heavy damage to their fragile frames.
==Notes==
*Whenever a Sentinel kills an enemy, the player only receives Warframe Affinity from the kill. Even if the player assisted in the kill, no weapon experience is awarded. Any experience gained through Affinity Orbs will be shared across all equipment.
*While using 's ability, your sentinel may periodically fire a bullet at your controlled foe.
*If a player remains idle for an extended period of time, a Sentinel will "disable," stopping its idle animation and causing it to not fire or use abilities, presumably to prevent players from idling. They can be re-enabled by moving several meters.
==Tips== 
*Because of the aforementioned Priority system, it may be wise to equip utility-based Precept mods (be it Sentinel-specific or general Sentinel mods) at higher priorities over attack Precept mods, so Sentinels can assist players immediately when the situation calls for it. 
** , , , and can be placed in any mod slot as their effects are inherently passive, thus they are not affected by Priority nor do they interfere with it. The same applies to mods that affect a Sentinel's stats directly.
==Trivia== 
*Interestingly, the data Fragments that players can scan on Mars seem to suggest that most of the early Sentinels were perhaps an offshoot of the Sentients that were (fortunately) non-aggressive upon their discovery, and were subsequently used to assist the Tenno during missions. This is reflected in how most Sentinels, particularly those of Tenno origin, tend to be more organic in appearance compared to those built by other factions (such as the Grineer-built Diriga).
==Media==
sentinel weapons.png|Robotic Weapons Selection
Warframe Sentinel's
Warframe Sentinel Tutorial-1
==Patch History==
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de:Wächter
es:Centinela
fr:Sentinelle
Category:Companion
Category:Update 7