how does buffy come back in season 6
Buffy the Vampire Slayer (season 6) At the beginning of season six Willow resurrects Buffy with a powerful spell. Although her friends believe that they have taken her out of Hell, Buffy had actually been in Heaven since her death (a fact that is revealed to her friends later in the season). She is therefore traumatized by her resurrection and this causes her to fall into a deep depression for most of the season.
Surprise (Buffy the Vampire Slayer) Buffy has a vivid dream (a very undead Drusilla dusts Angel) which she fears is prophetic and realises that Spike and Dru may still be alive. Oz finally asks Willow out on a date. She accepts, but remembers the Scoobies are planning a surprise party for Buffy's 17th birthday and instead invites him to the party. Elsewhere, Dru, strong as Buffy dreamed, arranges her own gala event, while Spike, using a wheelchair but quite undead as well, directs his gang to collect scattered pieces of the demon Judge to reassemble for her present. Jenny Calendar gets a visit from a mysterious man who reveals Miss Calendar's Gypsy past, and they discuss her responsibilities in ensuring Angel's continued suffering. The man orders Jenny to separate Angel from the Slayer, Jenny agrees and she reveals that the man is her uncle. On their way to Buffy's surprise party, she and Miss Calendar intercept a piece of the Judge and bring it to the party, deducing Dru's plot. Following her Gypsy orders, Jenny encourages Angel on his mission to prevent the dire consequences of reassemblyâ€”he must take the Judge's arm by cargo ship to "the remotest region possible." While Angel gives Buffy a Claddagh ring for her birthday during their tearful parting at the dock, Spike's vamps manage to steal the arm back, scrubbing the mission. Later at the library, Buffy has another informative dream, and takes Angel to investigate the factory where Spike and Dru have their lair. They discover the Judge is fully assembled and activated, and Spike and Drusilla capture and taunt the two, debating who will die first. They narrowly escape into the sewer system, then return to Angel's apartment exhausted and drenched from the rain. Still suffering from successive threats of losing one another, Angel and Buffy confess feelings each has been trying to suppress. They make love for the first time and fall asleep in each other's arms. Suddenly, in a flash of lightning and a crash of thunder, Angel bolts awake and runs out into the storm, calling Buffy's name in anguish.