Nightmare

The Nightmare is a hostile Typhon encountered on Talos I during Prey (2017).

Overview
The Nightmare is the second biggest, strongest and most dangerous of all the Typhon. Created as a form of response due to the Typhon seeing Morgan Yu as a threat to their species, as Yu unlocks more Typhon powers through neuromods, this action will attract Nightmare attention, provoking it to hunt Morgan down. It will start its hunt after Morgan goes to Deep Storage.*

* It can start hunting after spending enough Neuromod points on multiple Typhon skills at once. Not necessarily after Deep Storage(**).

** It can also start its hunt after you gain access to the lift in the lobby, even if you have no Typhon skills whatsoever. The circumstances it can do such are currently unknown but may be linked to total Neuromods used.

Other terms is when you has just resetted the Neuromod's license or most likely if player already have more than 20 Neuromods.

The first sign of Nightmare appeared at that area is Talos I will receive earthquake and January will warn you that you're being hunted by Nightmare. Everytime Nightmare appears, Talos I will be shakaned and you got three minutes to evade or kill Nightmare on side quest once it's alerted of your presence.

Killing it will cause it to respawn 30 minutes later, where as running away and exhausting the timer will cause it to respawn 20 minutes later.

Design
Nightmares look like a bulkier version of a Phantom. They posses six white spots that can merge into one, which serve as eyes and seem to float around instead of walking. Nightmare can also shapeshift to better suit doorways.

Strategy

 * Hide until the Nightmare's associated side quest time is exhausted.
 * Gloo can work for a duration currently thought to be under 10 seconds. Useful for scanning more than offence.
 * Chaining several recycler grenades seems to be the safest method for a kill.
 * Circle strafing with a shotgun (especially upgraded) can often result in a quick kill.
 * If lucky it will spawn in as you are getting on or off the elevator. At that point you are safe from its attacks and can wait out the hunt in the elevator. Then go to a different area for a brief time and head back and it will be gone but it will be marked as you have evaded Nightmare and it will respawned 20 minutes later.
 * Turrets are often not very effective, but in certain areas the Nightmare can be trapped within firing range yet unable to hit the turrets, resulting in a guaranteed (if slow) kill.
 * Nightmare is vulnerable to psi abilities. Four uses of fully upgraded Psychoshock is enough to kill it.
 * The Nightmare is also susceptible to Mindjack, which will allow the player to escape and hide, while also making the powerful Nightmare sweep the area for other Typhon that often accompany it.
 * Nightmare cannot go to the entrance of Power Plant if player encounters it at Life Support area. Sneak attack damage should be sufficient enough to defeat it without taking risk of being hit if player do it carefully.
 * If possible barricade a doorway with large items using the leverage ability, keeping yourself out of its melee range and blocking it's energy balls.
 * The Side Quest will not be started until Nightmare was alerted of your presence. If you found Nightmare is sitting duck and do nothing then the Side Quest will not be started. Sneak away from it if you met Nightmare on open field such as Arboretum to avoid triggering side quest because when its alerted the countdown will be started.
 * Nightmare will disappears once the timer goes out regardless any remaining HP on it. If you really want to kill it then kill it before timer expired.
 * If Nightmare spawns at where Dahl's Military Operator is everywhere (Shuttle Bay or Arboretum), let the Military Operator do their work and you do not need to fight it. Timer will usually start but you don't need to fight it since even Military Operator is your enemy (If you haven't hacked it with Hack IV), it will also considers Typhon enemies as a threat.

Trivia

 * Nightmare is reminiscent of the Nemesis monster from Resident Evil 3
 * This is the only side quest that can be repeated many times. When it respawned and notices your presence, the countdown timer and side quest will be started.