Nightmare Mode

Nightmare Mode is a set of random challenges that can modify the 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 (unconfirmed). Challenges for this mode can be mixed up with others.

Upon completion of the mission, you will be rewarded by a special, Rare mod with dual effects.

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: Your health will be reduced by 3 (unconfirmed for different levels and Warframes) every second. The death of enemies (this includes Infested Chargers exploding) will increase your health.
 * Timer: The mission will now be timed, starting at between 3 and 5 minutes. The death of enemies will add onto your timer.
 * Low Gravity: The gravity will be reduced approximately by half, causing less control for your jumps. This also affects enemies.

Mod List
These are the mods obtainable from completing a mission in Nightmare Mode. This is an incomplete list. Help fill it!
 * Ice Storm
 * Wildfire
 * Fortitude

Mission Rewards
Possible Rewards on completion include:
 * Constitution
 * Accelerated Blast
 * Focus Energy
 * Wildfire
 * Hammer Shot
 * Rending Strike
 * Ice Storm

Known Bugs

 * Host Migration will sometimes cause enemies to revert to standard mission level, and special circumstances (timer, hp reduc, etc) to be removed. Mission will still reward as nightmare mode however.
 * The Vampire effect will take effect as soon as the mission begins, from the beggining cutscene, to when you can actually move around.