Excalibur Umbra, who possesses sentience and abnormal memories linked to Ballas that the Tenno seek to suppress, uncovering the horrifying origin of the Warframes in the process.
The Sacrifice is a solo-only main Quest, released in Update 23.0 (2018-06-15). After the Lotus has been taken by Ballas for unknown reasons, the Tenno discover a new Warframe, Excalibur Umbra, who possesses sentience and abnormal memories linked to Ballas that the Tenno seek to suppress, uncovering the horrifying origin of the Warframes in the process.
The Tenno hears faint whispers of the recently abandoned Lotus. Her voice directs them towards her helmet within the Orbiter's Personal Quarters. As the Operator touches the helmet, visions of a Warframe being restrained by Ballas and Sentient fighters flow in their mind, prompting them towards Earth to investigate.
The Warframe in question, Excalibur Umbra, was out of sight — only his remains survived his fight with the Sentients. Ordis attempts to recreate him in the Foundry based on scans of his remains but lacks sufficient data to do so. Trace minerals on Umbra's 
Skiajati Nikana suggest that more information can be found on Lua. A visit to Lua yielded a Vitruvian device found within a containment lab that belonged to Ballas. This Vitruvian contained recordings made by Ballas on his betrayal to the Orokin during The Old War and the origin of Warframes. Uploading the Vitruvian into the ship's mainframe gave the ability to craft Excalibur Umbra. Upon equipping him in the Arsenal, he immediately goes berserk and damages his own helmet to reveal an eye, then pins the Operator into a wall until they enter his mind using Transference. The Tenno learns of Umbra's origins as a personal punishment from Ballas upon a Dax soldier for spying on him during his late betrayal of the Orokin. The Dax soldier was subjected to injections of a Helminth Infestation strain to produce skin-grafted armor and modified organs, akin to the typical Warframe design process during the Old War.
The memory abruptly ends, and the Operator finds out that Umbra has escaped the ship, rejecting Transference. They chase down Umbra as more entries of the Vitruvian become unlocked by accessing his memories. He contains the key to the secrets of the Warframes themselves.
After multiple tries, the Operator eventually accesses Umbra's final memory: killing his own son Isaah when the Infestation takes over his body and Ballas forces him to act through the modified Transference Bolt. The Operator intervenes in this event, telling Umbra that he doesn't have to relive this event in solitude, instead, they will face this grief together through the duality of mind and body. Umbra as the hand, the Operator as the soul.
In this revelation, the minds of Umbra and the Operator are linked — Transference was successful. With this newfound power, the Operator and Umbra fend off a Sentient assault and return to Earth to face Ballas.
During the final confrontation, Umbra successfully stabs Ballas in the gut, defying Ballas' subjugation thanks to the Operator. After questioning him on the whereabouts of the Lotus, she appears from the sky in a Sentient battle form, taking Ballas with her as she returns back to her Mother. The Lotus seems to no longer be the motherly figure that the Tenno loved.
After completing Apostasy Prologue, players may start this quest in the Codex.
On starting the quest, the Lotus's whisper can be heard, calling for the Tenno. The player is prompted to examine her helmet in the Orbiter's Personal Quarters. The Operator touches the helmet and sees a vision of a black and gold Warframe being subdued and obliterated on Earth by Ballas and Sentients.
On landing, Grineer Ghouls lie in wait. Follow the waypoint, leading to an Orokin door covered in vines which must be destroyed. As the door mechanism slowly opens, swarms of Ghouls appear and attack. Behind the door leads to a large courtyard, the same one shown in the Operator's vision. Equip the Codex Scanner or Synthesis Scanner (Helios will work as well) and search around for traces of the Warframe (looking from the entrance towards the cherry blossom tree):
Skiajati nikana - embedded right next to the treeOnce this is accomplished, extraction awaits, with Ghouls preparing for another ambush.
Ordis has synthesized the discovered traces in the Foundry as a new Warframe: Excalibur Umbra. However, the data to build this Warframe is insufficient. Remembering that Ordis detected trace minerals from Lua on the nikana, the Operator suggests searching there.
The Operator tells Ordis that Excalibur Umbra tried to attack Ballas, surprising Ordis as Warframes were supposed to be controlled through Transference. The waypoint leads to a unique Orokin Memory Cipher terminal that cannot be bypassed, so Ordis suggests searching the area for clues. As it is a memory cipher, that is it requires the correct sequence as a genuine memory from the user, it cannot be brute-forced even with the correct sequence until all parts have been memorized by the Operator. There are two blue symbol pairs around the area; to solve the Cipher, players must match the cipher to the order of the symbol pairs discovered (the player does not have to actually remember the sequences themselves, the game will show them.) Beyond the unlocked door, Sentient Mimics lie in ambush; these Old War Sentients carry beam rifles and have the same damage resistances as Battalysts and Conculysts do.
View of the cipher on the Lua Somachord Room.
Up ahead is yet another Orokin Cipher, with four symbol pairs nearby. Also in the room with the cipher is a Somachord fragment high up on the rafters. This cipher is more complex, and the discovered symbols will rearrange themselves above the cipher rings when you complete partial solutions. Should the player take too long with the sequence, Ordis will help solve the puzzle automatically. The cipher unlocks a dome that Ordis believes to have contained Excalibur Umbra. Somewhere inside the dome is an Orokin tablet, containing a spiraling series of recurring glyphs, with the single one interactable highlighted blue: "Enemy". This entry, a voice recording by Ballas, states the codices within reveal a hidden weakness to the Warframes. Ordis identifies the tablet as a Vitruvian and suggests destroying it, but the Operator decides to take it back to extraction for analysis. Upon extraction, the player will earn 60 
Kuva.
In the Orbiter is an area where the Vitruvian can be inserted. When the Vitruvian is inserted Ordis expresses his regret at not being more forceful in rejecting the Operator's orders, before the Orbiter tilts and all its lights turn off momentarily. Ordis regains control, but his "vestigial" precepts regulating his ability to "care" about things have been knocked offline, causing him to display a new, emotionless personality, and he calls the Operator "Star-Child," with a faint view of a small robot body behind his usual icon. He tells the Operator to check the Foundry again, where Excalibur Umbra can now be built.
When the Operator attempts to equip Excalibur Umbra in the Arsenal, he unexpectedly rejects the Transference, displaying sentience as he lashes out against the Operator. During the struggle, the Operator manages to perform Transference on Excalibur Umbra and accesses a memory.
The memory is of a man lying in a hospital bed who has fallen ill and is unable to speak, with Ballas and a Dax soldier - who turns out to be the man's son called Isaah - by his bedside, with Ballas telepathically conversing with the man and threatening to kill his son. Excalibur Umbra escapes the Orbiter, but seeing Isaah in the memory unlocks a symbol within the Vitruvian, "Blasphemy", where Ballas curses the Sentients for their betrayal and starting the Old War.
Realizing the Vitruvian codes are locked within Excalibur Umbra's memories, the Operator proceeds to track him down. On Ceres, Excalibur Umbra is engaged in battle with the Grineer, having left a trail of bodies in his path. While en route, a Somachord fragment can be found on the scaffolding of a large crane (may not always spawn). When confronted, Excalibur Umbra is already battling the Grineer and is impervious to all damage, while his attacks ignore the Void Mode's immunity. Using Void Sling will stun Excalibur Umbra, allowing Transference to be used on him.
In this memory, the man and Ballas are playing a game of Komi. After a few rounds, Ballas commends the man's heroism and points out a commissioned portrait of his servitude as a Dax. Looking at the portrait unlocks another Vitruvian symbol. As Ballas asks Isaah if he will follow his father's footsteps, Ballas telepathically threatens the figure stating that the "game" of Komi represents Ballas culling the figure's bloodline for attempting to interfere with Ballas's defection.
Excalibur Umbra escapes again, and the Operator returns to the Orbiter. On the way to extraction, Sentient Conculysts appear on the scene. The next Vitruvian symbol, "Warframes", has Ballas reveal that the recordings are intended to reveal secrets to Hunhow, about how the Warframes were created from human subjects as Infested-hybrids converted by the Helminth as a means to fight against the Sentients. However, Ballas calls the Warframes a failure as they turned on their creators, but there lies a secret hidden within the Void.
Ordis reboots out of his new personality and urges the Operator to stop due to potential dangers. However, the Operator is undeterred, believing that Excalibur Umbra is leading to something.
Many dead Corpus lie ahead. Excalibur Umbra kills all the Sentients within his vicinity and uses 
Radial Howl to escape, leaving the Operator trapped by Mimics. A Somachord fragment appears in this area. When Excalibur Umbra is confronted again, he is once again invulnerable to Warframe attacks, and now has shields that prevent him from being affected by Void Sling. During this fight, Umbra’s attacks will also be able to damage the Operator even when they are in Void Mode. Shooting down the shields with the Void Beam and stunning Excalibur Umbra with Void Sling leaves him open for Transference and allows the Operator to go into another memory.
In this memory, the man has difficulty breathing with Infested growth appearing in his vision as he is losing to Ballas at Komi. Isaah then points to the man's Shawzin instrument, unlocking another Vitruvian symbol, as the game of Komi resumes. Ballas telepathically monologues that he betrayed the Orokin after several lifetimes of planning since they had killed Margulis, and informs the man that the Infested cultivates within him, slowly transforming him into a Warframe. Not just any Warframe, but one that will have a single, burning memory through a miracle that requires a sacrifice. Hearing this, the man mistakenly places his Komi stone into a trap.
Through the memories the Operator realizes that Ballas intends to kill Isaah and briefly refers to him as "my... his... son", confusing Ordis as these are just memories. The next Vitruvian symbol, "Tenno", tells of how the Orokin kept the survivors of the Zariman in the Reservoir, using Transference to merge Tenno's minds into the bodies of the Warframes. This entry also reveals that Ballas had sent coordinates to the Reservoir to Hunhow, but warns him not to underestimate the Tenno "monsters", as they have done what the Orokin couldn't.
Unwilling to hear the rest of the recording because they have lived that part themselves, the Operator abruptly cuts off the Vitruvian and uses Transference to appear at the Navigation console, intending to confront Excalibur Umbra alone.
The Operator appears in this mission alone, telling Ordis that "their Warframe" is there and needs to be found. Excalibur Umbra once again must have his shields shot down with Void Beam, stunned with Void Sling, and his mind entered with Transference.
This time, the Operator appears in Excalibur Umbra's final memory as he is instructed by Ballas to kill Isaah - to make the sacrifice that will create the single burning memory - to finish the miracle. The Operator tells Umbra that Ballas is at fault and they will fight him together. After the memory, the Operator appears within a black-and-gold space with a single path and a large tree at the end. Following the path, the Operator hears Isaah's voice from the memories. At the end of the path, the Operator finds Excalibur Umbra crying, and kneels. Excalibur Umbra eventually becomes at ease with the Operator's presence and finally accepts Transference, as the previously cut-off Vitruvian recording monologues that the Orokin broke the minds of the Warframes, but the Tenno, through their experience on the Zariman, were somehow able to see inside the broken creature and take away its pain. A dialogue choice is prompted to the player:
The player now has complete control over Excalibur Umbra, who is automatically at level 30 and armed with the Skiajati nikana and pre-installed with the mods 
Umbral Intensify, Umbral Fiber, Umbral Vitality, Sacrificial Steel and Sacrificial Pressure. In addition to having Excalibur's powers, 
Radial Blind is upgraded into Radial Howl which removes Sentient resistances, and Excalibur Umbra's sentience allows him to fight on his own when not piloted by the Operator. Sentients arrive and must be dealt with before heading to extraction, impeded by more Sentients as well as Corrupted. A Somachord fragment can be found in a cave in the room where Excalibur Umbra is fought.
At the Orbiter, the Operator now seeks to hunt down Ballas, but tells Ordis to play a recording of the Lotus's voice. Ordis asks what recording he should play:
The Operator and Excalibur Umbra return to the courtyard on Earth to confront Ballas. Surprised at the turn of events, Ballas declares both will burn and sets a tree ablaze while projecting a shield around him as Sentients arrive to fight. After disposing the Sentients, Ballas commands Excalibur Umbra to stop, forcefully halting his movements through the modified transference bolt. Ballas boasts and approaches the paralyzed Warframe, only to discover the Skiajati impaling him. Excalibur Umbra momentarily hesitates and tries to release his grip before being stopped by the Operator, who is revealed to be holding Umbra's arm, and drives the blade further in and proceeds to taunt Ballas with the following options:
Ballas seemingly succumbs from his wounds as more Sentients arrive. As the Operator demands the Lotus's whereabouts from Ballas, a much larger Sentient drops in: Natah – in a sentient battle form. She claims that Ballas had done nothing to her and that this is what she is. The surrounding Sentients open fire on the Operator, but is taken to safety by Excalibur Umbra. Natah picks up Ballas's body before leaving a cryptic warning: "Mother... I am coming home". She then flies off and disappears.
Back on the Orbiter, Ordis and the Operator are confused and in disbelief at the sudden turn of events, and the Operator then expresses resolve in finding out the truth.
A new inbox message will be given upon completion of the quest, giving players the Excalibur Umbra Sunder Helmet, the Umbra's Courtyard Scene for Captura, and Excalibur Umbra Agile and Noble animation sets.
Following completion of quest, if the player encounters The Man in The Wall, they will ask the Operator if they are "feeling better, kiddo?" The Operator responds "I killed him... Isaah." After confirming that is how the Operator remembers it, the Man in The Wall responds "Good", and vanishes.
Skiajati will be automatically equipped while carrying over any installed mods and altered appearances. A second Skiajati and set of Umbra Mods will not be given.
Update 36.0 (2024-06-18)
Update 35.5 (2024-03-27)
Other Quest Changes:
Update 35.1 (2024-02-20)
The next batch of changes to improve the new player experience are here! In this update, we address Quest progress obstacles to make them more accessible.
Quest Changes
The Sacrifice Quest Changes:
Update 34.0 (2023-10-18)
Update 32.2 (2022-11-30)
Update 32.0 (2022-09-07)
Hotfix 31.7.2 (2022-08-17)
Update 31.6 (2022-06-09)
Update 31.5 (2022-04-27)
Hotfix 31.0.8 (2022-01-12)
Hotfix 30.0.6 (2021-04-20)
Update 29.10 (2021-03-19)
Hotfix 29.6.4 (2021-01-06)
Hotfix 29.0.3 (2020-08-26)
Update 28.3 (2020-08-12)
Hotfix 28.2.1 (2020-08-01)
Update 28.0 (2020-06-11)
Update 27.2 (2020-03-05)
Hotfix 27.0.11.2 (2020-01-16)
Hotfix 25.5.1 (2019-08-02)
Hotfix 25.4.1 (2019-07-24)
Hotfix 25.3.2 (2019-07-12)
Hotfix 23.6.2 (2018-08-31)
Hotfix 23.3.2 (2018-08-13)
Update 23.3 (2018-08-09)
Update 23.2 (2018-08-02)
Hotfix 23.1.3 (2018-07-26)
Hotfix 23.1.2 (2018-07-24)
Hotfix 23.1.1 (2018-07-19)
Update 23.1 (2018-07-18)
Hotfix 23.0.7 (2018-06-28)
Hotfix 23.0.6 (2018-06-27)
Hotfix 23.0.4 (2018-06-20)
Hotfix 23.0.3 (2018-06-19)
Hotfix 23.0.2.1 (2018-06-15)
Hotfix 23.0.2 (2018-06-15)
Hotfix 23.0.1 (2018-06-15)
Update 23.0 (2018-06-15)
Last updated: Hotfix 25.5.1 (2019-08-02)
