Prophetic dreaming

“Well, it definitely could be one of your prophetic dreams, or it could just be the eternal mystery that is your brain”

―Rupert Giles talking about a dream Buffy Summers had.

Buffy experiences a prophetic dream

Prophetic Dreaming was the ability to perceive the future in the form of vague dream sequences. It was one of the main powers possessed by the Slayer.

Description

Slayer would, on occasion, experience dreams that foretold future events, whether it was a threat that's imminent or in years to come, if it was long term or an easily dealt-with situation or if it wasn't a threat anyway. 

These dreams could consist of a bizarre situation hinting upcoming events through visual or spoken cues  or could just show the actual event itself, and were not strictly precognitive as Slayers, both Potential or activated, would experience dreams of the lives of past Slayers, and could even experience dreams that revealed facts about the present.. Two existing Slayers would also form a psychic link, allowing them to share dreams.

Buffy Summers

Buffy Summers has experienced prophetic dreams time-to-time, and the size of the threat would vary.

• During her first day at Sunnydale High in 1997, before waking up, Buffy dreamed of the various experiences she eventually faced in future, including books about the Harvest, the last member of the Brotherhood of Seven, the origin of Moloch the Corrupter and presence of the Master.
• Buffy had once a dream where she is killed by the Master, foreshadowing their future fight.
• Two months after his fate, Buffy dreamed of a resurrected Master, disguised as Giles, attacking her. This dream foreshadowed his attempted return, orchestrated by Colin and Absalom.
• During her 17th birthday, Buffy experienced a dream set at the Bronze between her and her lover Angel, joined by her mother, Willow Rosenberg and completely cured Drusilla, revealing that Drusilla has been restored even though she was presumed dead. In the dream, her mother asked her if she's ready just before Buffy walked over to meet Angel on the dance floor, both happy to see each other, symbolizing their growing feelings and intimacy. Drusilla then appeared from behind Angel and staked him, ending the dream. Buffy experienced another dream the same night, now involving featuring Angel being decapitated by Drusilla at the factory. These dreams foreshadow the loss of Angel's soul along with Drusilla's involvement in making it happen by causing the chemistry between Buffy and Angel to ignite due to the pressure and co-dependence put on them with her plan to awaken the Judge. The following day, after the loss of Angel's soul, Buffy experienced a third dream which consisted of Buffy and Angel making love, only to move into a cemetery with Angel (now Angelus) and Jenny Calendar, revealing that she tried to keep Buffy and Angel away from each other to prevent the loss of his soul.
• While sick with a fever in the hospital, Buffy has a dream where at 2:27 in the morning she wakes up to see Ryan outside her door. As he leaves, he is followed by Der Kindestod who looks in Buffy's room briefly. Buffy follows the two, having flashes of walking down another hospital hallway as a little girl and going into her cousin Celia's room. Buffy then wakes up at 2:27 and though neither Ryan or Der Kindestod are there, Der Kindestod has killed a little girl. The dream signifies how Der Kindestod is stalking Ryan and the other children in the hospital and how he can only be seen by those who are sick, like Buffy was at the time of the dream. It was also showing that Der Kindestod killed Celia.
• Buffy has a nightmare where she does some Slayer training in an old Spanish Mission only to be transported to the sunken church and encounter the Master and three nasty demons before the Master drains her. The dream predicts the return of the Master and the appearance of the Dreamers in his plans.
• Buffy has a nightmare in which she tries to escape murky waters while the murdered Allan Finch pulls her down. Finally reaching the surface, Buffy sees Faith Lehane, who immediately pushes her fellow Slayer back underwater. This dream foreshadow Faith's involvement with the evil forces.
• While unconscious in hospital, Buffy shared a prophetic dream with Faith Lehane, who was in a coma at the time. Both Slayers were inside Faith's apartment and shared a dialogue that hinted at the arrival of Buffy's little sister Dawn represented by a cat, as Faith claimed "Little Miss Muffet counting down from 7-3-0", 730 days being 2 years which was the time before Dawn's arrival before this dream.
• Buffy experienced a dream while asleep during Psych class. In the dream, Maggie Walsh had Buffy lie down in front of the whole class before being kissed by Riley Finn. Just as they embraced, the room went dark. Buffy walked through the halls of UC Sunnydale to find a little girl holding the Gentlemen's box and singing a disturbing lullaby describing the actions of the Gentlemen. Buffy then saw one of the Gentlemen embodied in Riley. The dream foreshadowed the arrival of the Gentlemen in Sunnydale while Maggie's speech about communication represented the lack of communication between Buffy and Riley to their secret lives.
• Buffy, along with Giles, Xander, and Willow shared a sequence of dreams in the episode Restless. Some of the instances in the dreams were foreshadowing, such as Buffy's mother, Joyce, obtaining a brain tumor in season 5, Dawn's introduction, etc. [14]
• Buffy dreamed of her now deceased mother, Joyce, taking to her while Buffy was in the middle of research. Joyce told her to get some rest, as Buffy was without sleep for days, causing her to be beaten to a bloody pulp by the Turok-Han vampire during their first encounter.
• During 2002-2003, Buffy was in conflict with the First Evil and in the meantime, was protecting and training the remaining Potential Slayers. In the dream, Buffy was walking inside her home only to be attacked by the First Slayer, telling Buffy "It is not enough!". This represented how Buffy had to evasive actions if she wished to deal with the First's threat, leading her to confront the Shadow men.
• In 2005, Buffy had a dream of her and Xander Harris going to bed in their castle in Scotland. Buffy then advances on Xander, kissing him on the lips, causing his head to pop off his body. A loud gust of wind then breaks through the window and blows violently into the room. Just before she was pulled into it, Buffy cried "No, I can't go outside I'm afraid of the dark!" with Xander's disembodied head replying "Buffy, you are the dark." which was what Buffy meant. Buffy then began to fall into a chasm of fire, only for her fall to be broken by the claw of a giant demon, his fingernails piercing into her hands and feet. Buffy recognized the demon before it incinerated her. This dream symbolized her growing attraction to Xander as well as the feeling that she should be punished. The cause of this was due to a spell cast by Amy Madison, putting Buffy in permanent sleep until she was kissed by someone who loved her. Buffy was then contacted by Ethan Rayne, who entered her body via astral projection.
• Buffy had dream where she fell on the floor of the sunken church. She then encountered Caleb along with Spike and Angel. Buffy claimed that she missed either Spike or Angel, but it wasn't shown who she missed. Ignoring Buffy, the two vampires then made-out in front of Buffy and Caleb, representing her enjoyment at the idea of Spike and Angel being intimate together. The dream then moved to a wedding ceremony. Warren Mears as the groom, Buffy as the happy bride, Caleb at the altar, Xander as best man and Tara as the bridesmaid wearing the outfit she died in, telling Buffy she blames her for her death. The guests consisted of several demons (like Sweet, some Vampy cats and the Gentlemen) along with a sad-looking Willow sitting next to her evil counterpart. The dream then ended with Buffy sitting grimly in a kitchen having her breakfast, with a caricature of Xander asking Buffy if she was sleeping any better, only for Buffy to respond "Everybody die always". The dream symbolized how Buffy questioned the moral implications of creating a Slayer army, comparing herself to Caleb and his army of Bringers and Turok-Han vampire. The wedding symbolized how Buffy started to feel that she was among the monsters and her secret guilt over Tara's death. Also, the outfit Buffy wore in the church was the same as the one she would wear in the church when finding the Seed of Wonder.

Faith Lehane

Faith had dreams, mostly involving her fellow Slayer Buffy.

• Faith was struck in a coma after being stabbed by Buffy. She shared a dream with her at the place of where they fought where Faith hinted at Dawn's arrival before looking at a bunch of boxes. Buffy wondered if they'll be packed up, but Faith says they're here to stay, meaning Buffy must take on the role as a full time Slayer since Faith was then comatose.
• The day Faith awoke from her coma, she experienced two prophetic dreams. This included her and Buffy making a bed, again hinting Dawn's arrival. It ended with Buffy's hand holding onto the knife that she used to stab Faith, sticking in Faith's stomach, showing how Faith views Buffy as a murderer. The next involved Faith having a picnic with Mayor Wilkins, who she viewed as a father. Buffy then interrupted the picnic by slashing the Mayor with the knife. Faith, now dressed in her street clothes opposed to the cardigan she was wearing before, ran away from Buffy who followed her into the cemetery. It ended with the Slayers falling into an open grave, fighting to the death, with Faith emerging from the grave victorious, ending the dream and her coma.
• Faith, possibly due to the drug Orpheus, shared a dream with Angelus where they went through a walk in Angel's memories of his past deeds and misdeeds. After Willow shattered the Muo-Ping, Angel himself entered the dream as one of his past selves and he battled Angelus while trying to convince Faith to fight instead of giving up on life and redemption as she was close to doing. Angel finally managed to break through to Faith and she woke up in time to stop Connor from staking Angel. The dream continued for Angel and Angelus who fought to a draw until Willow restored Angel's soul, causing the two personas to merge in the dream.

Appearances

• "Welcome to the Hellmouth"
• "Nightmares"
• "When She Was Bad"
• "Surprise"
• "Innocence"
• "Consequences"
• "Graduation Day, Part Two"
• "Hush" 
• "This Year's Girl"
• "Restless"
• "Bring on the Night"
• "Get it Done"
• "Damage"
• "The Long Way Home, Part Three"
• "Always Darkest"