seeking_spike | It's been driving me nuts

I can't remember the title or the author, which is annoying cause I remember all of the details about the fic, or at least the part I read up to. It's one of those dimension-hopping fics. One part takes place in an AU season 3 with almost all the Scoobies either dead or in hiding and Willow's gone all evil. Buffy received some medallion thing from the PTBs that allows her to communicate with the person that has the other medallion, but she doesn't know it's Spike. Darth Willow sends her to the NFA battle to help and she meets up with our Spike. Confusion of mistaken identity insues and later they get to the battle where our Buffy is. Spike and Buffy have the lovers reunion they should have had and they win the battle. In the other dimension, Spike has gone to Sunnydale to kill Willow because he thinks she killed Buffy. He pretends to be wanting to kill his third slayer in order to help bring Buffy back. They do a spell, Spike shows up in LA and grabs the wrong Buffy, which of course means that our Spike follows as well as the other Buffy and Willow. The last part I remember reading is the group trying to figure out who should use what names in order to avoid confusion.

So, with that not-so-vague description, can anyone help a girl out?