I know it can be complicated, but I'll try to make it simple below:
FACT -> Blues pick right now is guaranteed to be 22nd at worst.
If Ottawa makes Round 3 - Blues pick moves up one spot
If Detroit makes Round 3 - Blues pick moves up one spot
If ONE OF Toronto or NY Rangers make Round 3 - Blues pick moves up one spot (BOTH of these team CANNOT make it to Round 3, has to be one or the other)
The Toronto/NY Rangers scenario is why some of us want to see them both win their game 7's tonight, because they would then face each other in Round #2 and one of them would have to make it to round #3 which would then guarantee the Blues pick would move up one more spot to 21st overall.
So, best case scenario all of Detroit, Ottawa, NY Rangers/Toronto make round 3, then Blues pick can moves up to 19th, and in that case (ALL of the above happening) The Penguins pick would have to also be 25th overall, because Penguins would have to lose out in round 2 for above to happen, as would Chicago.
So the end of the first round would look like this:
30th -> Cup Winner (Either Detroit, Ottawa, Toronto/NY Rangers, Los Angeles/San Jose)
29th -> Cup Finalist (Either Detroit, Ottawa, Toronto/NY Rangers, Los Angeles/San Jose)
28th -> Conference Final Loser #1 (Either Detroit, Ottawa, Toronto/NY Rangers, Los Angeles/San Jose)
27th -> Conference Final Loser #2 (Either Detroit, Ottawa, Toronto/NY Rangers, Los Angeles/San Jose)
26th -> Chicago
25th -> Pittsburgh (Flames)
......
19th -> Blues (Flames)
Clear as mud.