Nightmare Mode

Nightmare Mode is a set of random challenges that can modify a mission's difficulty. Missions that are selected for Nightmare Mode have a black skull next to the mission's details. These missions are selected at random daily. Challenges for this mode can be mixed with others. A Rare Nightmare mod with dual effects will be rewarded upon completion of a Nightmare Mode mission.

Nightmare Mode was added in Update 9.

Challenges
All Nightmare Mode enemies are significantly increased in strength, and sometimes replaced with more dangerous versions (ie. Grineer Lancer becomes Elite Lancer)


 * Vampire: All Tenno's health will be reduced by 1.5% of maximum per second (this value is rounded each time). The death of enemies (this includes Infested Runners exploding) will recover 15% health for the entire Tenno squad.
 * Timer: The mission will now be timed, starting at between 3 and 5 minutes. The death of enemies will add to the timer.
 * Low Gravity: The gravity will be reduced approximately by half, causing less control of jumps. This also affects enemies and loot.

Mission Rewards
Possible Rewards on completion include:

10 Dual stat Mods (2 each for Warframe, Rifle, Shotgun, Pistol, and Melee):

12 Faction "Bane" mods (3 per Rifle, Shotgun, Pistol and Melee for Grineer, Corpus, and Infested).

***THESE 'BANE MODS" DO NOT DROP FROM NIGHTMARE MODE COMPLETION AND SHOULD PROBABLY BE MOVED***

All "Bane" weapon mods increase damage by 5% per rank, and max out at 30%. The base equip cost is for these mods is 4, and they all have a polarity.
 * Bane of Corpus (Rifle)
 * Bane of Grineer (Rifle)
 * Bane of Infested (Rifle)
 * Cleanse Corpus (Shotgun)
 * Cleanse Grineer (Shotgun)
 * Cleanse Infested (Shotgun)
 * Expel Corpus (Pistol
 * Expel Grineer (Pistol)
 * Expel Infested (Pistol)
 * Smite Corpus (Melee)
 * Smite Grineer (Melee)
 * Smite Infested (Melee)

Known Bugs

 * Host Migration will sometimes cause enemies to revert to standard mission level, and special circumstances (Vampire, timer, gravity, etc) to be removed. Mission will still reward as nightmare mode however.
 * The Vampire effect (and the Timer challenge) will take effect as soon as the mission begins, i.e. as soon as the beginning cutscene starts.
 * The scaling of the Affinity gained from enemies, seems to be lower than the original levels of the enemies in the mission, rather than scaled up to the new levels for Nightmare Mode. The scaling for the Credits reward is normal, though.
 * The screen goes blank before loading some missions (currently known mission Mars - Ultor).

Trivia

 * You can't do Nightmare Mode at rank 0.
 * Low gravity is always accompanied by another challenge. (Unconfirmed)
 * You can't opt into the regular mission once you have unlocked the nightmare version. (needs testing)
 * Completing the same mission twice does not yield the same reward, similar to the Void.
 * More than 1 challenge mode can be applied with each mission. (e.g. the vampire effect and the low gravity effect in the same mission)
 * Mission lobby screens for nightmare missions have a red glow to them.
 * Missions which are Nightmare mode will change after a short period of time (example first the Mercury mission Caloris was a Nightmare mode mission and later the Mercury mission Elion was a Nightmare mode mission)
 * If not everyone in the lobby sees the mission as nightmare mode from the solar map, only the ones who do should select the mission for it to be nightmare, otherwise the normal mission will start instead