User blog comment:Victory awaits/The actual outcome of Apocalypse?/@comment-1975828-20161001085626

I don't think Lucifer wanted to fight Michael, not really, but Michael was certainly an obstacle he had to confront, or else die. Destroying the Host of Heaven was possible with Jesse Turner, so if the other angels wanted to try and stop him, he could use Jesse.

And even without Jesse, every angel besides Michael was weaker than Lucifer, and with Adam Milligan as a vessel, I believe Michael had a disadvantage, not much, but enough to help Lucifer win.

Lucifer's goal was to wipe out humanity. Period. He succeeded in "The End", thus there was a chance he could do so again during season 5's finale.