Nightmare Mode is an optional difficulty modifier introduced in Update 9.0. When Nightmare Mode is selected, up to two mission modifiers take effect that greatly increase the mission's difficulty, but completing the mission will reward players with Nightmare Mods, which positively affect two stats of a weapon, Warframe, or Companion.
To unlock Nightmare Mode on a given planet, one must complete all mission nodes on that planet
When Nightmare Mode is unlocked on a given planet (unlock all other nodes on said planet), the game randomly selects one mission node for Nightmare Mode every 8 hours, limiting the possible Nightmare missions (and thus, potential rewards) to 17 missions every 8 hours. After completing the Nightmare Mode mission for a given planet, a new mission node will be selected 8 hours after completion.
Mission nodes under the effects of Nightmare Mode have a scarlet background and a white swirl in lieu of a faction icon. Mission modifiers will also be listed next to the mission type. From Update 11.0 onwards you may choose whether to run the mission in Nightmare Mode or not. If some of the players in a given squad do not have Nightmare Mode unlocked, only those with it unlocked should initiate the mission vote or else the mission will start normally.
All enemies encountered in Nightmare Mode have significantly increased levels, as well as massively increased damage and enemy spawns compared to their standard levels. Ciphers may not be used during Hacking and failure to hack any console will result in an Electricity proc applied to the player. Any summoned allied Specter will immediately be hostile to all players (except Shockwave MOAs spawned from a MOA Cabinet Spawner), indicated by a reddish distorted glow. Environmental Hazards can also appear as usual.
Up to two of the following challenges may occur per mission, and each modifier has an equal chance of being selected.
Player and companion shields are reduced to zero.
Overshields created by Warframe abilities do not occur while this challenge is active.
Guardian Blast from the Vazarin school will still create Overshields.
This modifier is ignored if the mission type is Hijack. No other modifier will take its place.
By virtue of having no shields, this modifier has no effect on Inaros and Nidus.
As Hildryn's entire kit revolves around using Shields in lieu of Energy, she will not be able to use any of her abilities during this modifier as she has no shield.
This modifier also affects the hostage in a Nightmare Rescue mission.
The mission has a 5-minute timer that will fail the mission if it runs down. Killing enemies will add 5 seconds to the timer.
Enemies dying from sources other than players (such as environmental hazards) will not contribute to the timer. Security Cameras and Corpus Turrets will contribute to the timer, however.
Below are the possible Nightmare Mode Mods that can be rewarded upon completing a Nightmare Mode mission. There are three pools of rewards that the Nightmare mission will pull from. These pools are based on the Planet where the Nightmare mission takes place, regardless of node level. Rescue missions have the potential to draw from any of the three reward pools based on the achievements performed throughout the mission:
Rescue missions may have their nightmare mod reward tied to the tier of the specter blueprint gained at the end of the mission, sometimes causing a nightmare mod reward from a higher difficulty tier to be rewarded on a lower difficulty planet.