"The king's reach is weaker here in the Undercroft. On the surface, I suspect this Warframe would be a liability, attracting his every wyrm. But here, you can roam free and revel in its power."
—Teshin
The Undercroft is a sub-realm located in Duviri, which can only be accessed by traveling through an Undercroft Portal.
The Undercroft is primarily featured in The Circuit.
Lore[]
The veil between the world of the Sol System and the kingdom of Duviri is thin. Thinner still in the Undercroft, where our reality and Dominus Thrax's imagination collide. The Undercroft is a sub-realm of Duviri, that is located closer to the deep core of the Void,[1] and in turn, is less protected from its influence. It is only accessible via portals, which are strictly controlled by the Dominus.[2] Its link with the Paradox means that Undercroft's effects can be felt both in Duviri as well as the Origin System, located on the other side of the Wall: fighting against the enemies that wander the Undercroft can undo and prevent defeats suffered by the Tenno in the past,[3] by ensuring that the opposing enemies never existed.[4]
The Undercroft is a subrealm of duviri, seething with memories of what happened or will happen,[5][6] as well as with the nightmares of Dominus Thrax.[7][8] Due to this, Teshin encourages the Drifter to use it as a training ground,[9] and also as a way to repay the Tenno for helping them via the Paradox.[10] Whoever controls the Undercroft, controls Duviri,[11] which may be why Thrax is able to so easily influence it with his emotions.[12] However, Thrax's influence is generally weaker within the Undercroft, as he is unable to fully sense the Drifter's activities or reset time in a way that would affect them[13].
Thrax himself is said to be afraid of the Undercroft, which may be why the portals leading to it are heavily guarded. Additionally, Sythel states that Undercroft is located too close to a mysterious entity,[14] while Lodun attempts to send troops down into it in an attempt to stabilize it.[15] Virtually everyone agrees that the Undercroft is a chaotic region filled with hostile entities.
Overview[]
The Undercroft is a Warframe and Operator/Drifter only section of Duviri where you have use of your chosen Warframe and Weapons from Teshin's Cave.
Upon entering a Portal, your task is to use the tools granted to you in Teshin's Cave to survive the onslaught.
↑"Rune Marrow erupts from Duviri's core." - Rune Marrow description
↑"Access to the Undercroft is strictly controlled. We are lucky to have this undetected portal. Use it." - Teshin
↑"Many defensive battles within the Origin System were lost. Through the Paradox, you now have the chance to undo those defeats." - Teshin
↑"Confront the maddened ones who walk the Undercroft, the shadows of armies that do not yet exist. Ensure they never become fully real." - Teshin
↑"Duviri pretends it never happened, but the Undercroft remembers. The tragedy... the Zariman. Whatever calm you can bring to that tormented place, please, do so." - Luscinia
↑"Acrithis tells me the Void is emotions keeper. Nowhere is the Void stronger than in the Undercroft. Why does it howl so? Please, answer its cry." - Luscinia
↑"Ah, the Undercroft! A seething mass of Void-ridden potential, spiced with childish nightmares. Give me some." - Bombastine
↑"You have to go to the place where bad dreams are real. The Undercroft. Whatever's wrong there, make it right. Hurry!"- Sythel
↑"The endless challenge of the Undercroft makes it an ideal training ground. Hone your skills there, if you have the stamina" - Teshin
↑"The Other Side has assisted you many times. The Undercroft is where you may repay them, with blood." - Teshin
↑"Whoever controls the Undercroft grasps all of Duviri by the roots. I won't let its reputation stand in the way of claiming what's mine. Get in, and do what you have to." - Bombastine
↑"Thrax's 'power' is rooted in the Undercroft. Pff. Without it he's not that big of a deal. Not really. Perhaps you should make your way inside, for a little 'takeover bid." - Bombastine
↑"The king's reach is weaker here in the Undercroft. On the surface, I suspect this Warframe would be a liability, attracting his every wyrm. But here, you can roam free and revel in its power." - Teshin
↑"Everyone's afraid of the Undercroft. Even Thrax. It's too close to the Void. To... to HIM. That's why I'm sending you in there." - Sythel
↑"Does that brat on the throne have ANY IDEA how often I've had to send forces into the Undercroft to clean up his mess? Maybe you'll do a better job. See what's amiss." - Lodun
↑Prelude to War is a compilation of miniquests and cutscenes leading up to The New War.
↑While not part of the main story quest, The Duviri Paradox has very interlinked story context to several critical characters in The New War.