Ok, so I'm new with this series-that's my excuse. Is Last Sacrifice the end of the Rose story and then the spin off starts?? Or...is LS the "crossover" end of Rose and beginning of the spin off or what?? Thanks...

LS is the last book from Rose's POV.
I'm not exactly sure how the Spin-off will start, but I suspect something big will happen in LS that'll create a reason for the spin-off to exist. But we'll have to wait and see for that one.

Wow you exsplain that really well i even got something out of that.