One element I think- the deer killing. Dark blood magic but one ingredient doesn't change the intent of the spell
It's about taking them into her - regardless of intent. If you think you are getting juice and you swallow bleach it's gonna have an impact even if your intent was not to cause permanent burns. It opened Willow to magics that were too hard to channel and they stayed with her. To me, this is what really fueled her spiral - an infection of sorts.
I got the impression from that conversation that they'd had the argument many times before and Xander- and the lay person when it comes to magic- is afraid to cross the finish line because it means commitment to something permenant- that's sort of his weak point this whole season.
Willow is honest about wanting Buffy back- and she thinks its the right thing to do, to rescue her friend. Tara thinks its wrong but wants to do it anyway- which is worse imv.
XANDER: It's just ... (fidgets nervously) It feels wrong.
TARA: It is wrong. (Willow looks surprised) It's against all the laws of nature, and practically impossible to do, but it's what we agreed to. If-if you guys are changing your minds-
WILLOW: Nobody's changing their minds. Period.
Willow is definitely bullying here - and she has gotten very powerful. We saw that in the opening scene. Everyone does speak up against it, but they are too tentative and Willow isn't listening.
I think Willow's memory alteration is a far worse crime than bringing Buffy back, Because the intent there ws sentirely selfish, not simply have aspects of selfishness.
I can see a case being made for that - but it really shows how far Willow slides. She's always been interested in dark magic, and always tried to help. Well, she got a buttload of dark magic and that started to push her over. She didn't even realize the line she crossed from helping others to helping herself by changing others. I see this as a culmination of a lot of decisions Willow made through the series, and I actually blame Giles for a lot of this.
Giles was raising demons for entertainment when he was this age - he knew the dangers. If he was going to use Willow as part of the Slayer-group then he really needed to train her instead of occasionally admonishing her. Willow kept dodging a bullet, and this was the season when she was hit. Joss said that the use of blood magic at the beginning of the season was why Tara died - you have to have an even exchange - a life for a life.
This is what makes the characters interesting to me - watching them stay themselves as they grow up. The kid who once asked Amy if they could pretend the magic they were using was dark is now the adult who is "doing magic" with Amy at Rack's.
Also I forgot Spike- if he counts as Buffy's friend- since he did terrible things to her this season. I'd say he was the winner.
I never saw him as a friend, though I suppose he was the only friend Buffy had in the beginning - the only person she felt she could talk to. Yeah, that was a toxic hot mess, but I still think Willow did worse. I'm not giving either of them points for intent. Some interesting parallels there, though - except Spike didn't have a soul.
Spike said that there were always consequences for doing magic. I don't think he meant it in a mystical way. Everything in the season goes back to Willow and the spell, and her infection of darkness.
GILES: (over his shoulder) You're a very stupid girl.
Willow pauses chewing, slowly stops smiling and frowns.
WILLOW: What? Giles...
GILES: (turns to face her) Do you have any idea what you've done? The forces you've harnessed, the lines you've crossed?
WILLOW: I thought you'd be ... impressed, or, or something.
GILES: Oh, don't worry, you've ... made a very deep impression. Of everyone here ... you were the one I trusted most to respect the forces of nature.
WILLOW: Are you saying you don't trust me?
GILES: (intensely) Think what you've done to Buffy.
WILLOW: I brought her back!
GILES: At incredible risk!
WILLOW: Risk? Of what? Making her deader?
GILES: Of killing us all. Unleashing hell on Earth, I mean, shall I go on?
WILLOW: No! (stands) Giles, I did what I had to do. I did what nobody else could do.
GILES: Oh, there are others in this world who can do what you did. You just don't want to meet them. (turns away again)
WILLOW: No, probably not, but ... well, they're the bad guys. I'm not a bad guy. (upset) I brought Buffy back into this world, a-and maybe the word you should be looking for is "congratulations."
GILES: Having Buffy back in the world makes me feel ... indescribably wonderful, but I wouldn't congratulate you if you jumped off a cliff and happened to survive.
WILLOW: That's not what I did, Giles.
GILES: (angry) You were lucky.
WILLOW: I wasn't lucky. I was amazing. And how would you know? You weren't even there.
GILES: If I had been, I'd have bloody well stopped you. The magicks you channeled are more ferocious and primal than anything you can hope to understand, (even more angry) and you are lucky to be alive, you rank, arrogant amateur!
Giles angrily grabs his towel and turns to leave.
WILLOW: You're right.
He pauses by the door, looks back at her.
WILLOW: The magicks I used are very powerful. I'm very powerful. And maybe it's not such a good idea for you to piss me off.
Giles stares at her, then looks away. After a moment, Willow relents.
That's what I see - it's what they all go through this season.