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 the Nightmare's arrival is a brief shake of the station, followed by a loud roar produced by the creature itself. This is not a guarantee, as the Nightmare can spawn in another area you have just entered and your only warning will be by spotting it. Each time the Nightmare has spawned, you will have three minutes to evade or kill it before the timer runs out and it despawns.

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. Like almost all Typhon, it is a mass of tentacles and shifting matter. They posses six white spots that can merge into one, which serve as makeshift eyes. The Nightmare's "head" is actually, in fact, four to six mandibles that have conjoined to form the shape; These mandibles will split apart and spread out when it unleashes its main attack, accompanied by a roar. It is capable of squeezing through doorways, and appears to only take a humanoid shape for combat purposes.

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 start until Nightmare is alerted of your presence. If you found Nightmare patrolling and doing nothing then the Side Quest will not start. 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 expires.
 * 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.
 * If you complete You rang? Achievement or mission of placing the signal transmitter Satellite on Talos I exterior, you will be able to evade Nightmare everytime it spawns by playing some Transscribe that contains repelling Nightmare.
 * Summoning Nightmare is not recommended since you will waste more than what you gain from it unless you do it on purpose like calling it to distract the Military Operator so you can slip through.
 * Nightmare will not fit into tight spot such as under the table and tight alleyways (Such as Maintenance Tunnel or small gap where Nightmare can't reach it)
 * Nightmare will never spawn on Talos I exterior.

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.