Nyari's guide is great for unlocking and understanding nightmare mode, but I wanted to add some tips for completing nightmare missions.
--You should have a passing understanding of the Damage 2.0
system. The full up-to-date system is here: http://warframe.wikia.com/wiki/Damage_2.0
.The system is very complicated, but a basic explanation is:
Yellow (armor) health bar: weak to Puncture, toxin, and corrosive(Electric+toxin).
Blue (shield) health bar: weak to Impact, electric, and very weak to magnetic(electric+cold).
Red health bar: Weak to Slash, Fire, and blast(Fire+cold).
My general loadout is a primary weapon with puncture and corrosive, a secondary with magnetic and maybe impact, and a melee weapon with Slash and Blast. This will give you some ability to cover all situations. However, the nature of this set is that you will need to control the range of fights to match the weakness of your enemies. Having to run up to every red health bar enemy could be deadly on death detonation
--Overshields still apply in "no shield mode
." The easiest source of repeatable overshields is The Taxon sentinel's Molecular Conversion
effect. Shield restore items will instead provide overshields, but are less effective than health restores. A couple warframes have abilities that create overshields, but those are also the warframes with the least health and armor.
--the rhino warframe is easily acquired and makes no shield
mode a joke. The parts can be acquired from the assignation mission on Venus against the Jackal. Repeat until you have all three parts (chassis, neuroptics, and systems) and the blue purchased in the market for 35,000 credits. Rhino's iron skin ability absorbs damage like a shield. With no mods, at level thirty, it absorbs 1200 damage for 50 energy and lasts until depleted. Rhino's armor value x 2.5 is also added to the shield. Since armor prevents health damage, you'd want it high for no shield mode anyway. Steel fiber is a common mod to increase armor.
Rhino is also solid on "Energy drain mode.
" if you equip an energy efficiency mode, you can cast Iron Skin at the start of a mission or when you find an energy orb in a container. Rhino doesn't need his other abilities and tanks ok without Iron Skin, so he is less affected by energy drain. Rhino can ignore "death detonation mode
," too. With Iron Skin on he's immune to status effects. Iron Skin will deplete fast, so keep your distance.
--Valkyr has almost no shields normally and very high armor, so she is less affected by no shield mode. However, her basic frame is harder to acquire and she has a playstyle that requires practice. As I'm writing this, however, her Prime (improved) version is one of the easiest to acquire, so you may want to try her.
Inaros and Nidus both start with no shields, and therefore, suffer no penalty on the most common nightmare missions. Inaros is acquired from the Sands of Inaros
questline, which is acquired from the biweekly trader, Baro Ki'Teer.
--Some Warframes that you won't acquire until very late in the game have abilities that can be useful in nightmare mode. Equinox, Harrow, and Oberon have some healing abilities.
--For nightmare missions where you just want to run by the enemies, such as death detonation
, Nyx or Loki are excellent. Nyx's parts are acquired by killing Phorid during infested invasions. Her Mind Control and Chaos powers force enemies to fight themselves. Loki's Decoy or invisibility powers also let him slip by. These are harder to use than Rhino, but have more use in the outer planets.