I don't know of any magic words, except for NO. My daughter will try the same stuff - stalling, wanting one more story, one more hug and kiss from Daddy, a drink of water, etc., etc. At first it seemed sweet, and not unreasonable - after all, what's one more story or one more song for cuddles when they are little like this? But DD would just want more and more and I finally had to realize that I needed to be firm, set my limits, and just tell her NO. Because otherwise the bedtime routine was dragged out for an hour or more and it was just too much. DD will still sometimes put up a fight, but I'm the mom and I'm in charge, not her.
Before she lays down, make sure she's had one more trip to the potty and she's got whatever toys she needs, and then say good-night, and LEAVE. And if she asks for anything else, tell her NO, time to sleep, no more requests, good-night!