Puzzle of the week #80

Level: 
5-Queen
Chess Diagram: 

k---K---
-------b
--------
-pP-----
--------
-p-----B
--------
--------

Continuing the exploration of Troitsky's magical World of endgames, we will stop now at another very simple looking puzzle. This puzzle has been published for the first time in the magazine "Trudovaja Pravda" in 1927. It is said that anyone can play when there are lots of pieces on the board, but the true test of chess mastery comes in the endgame when resources are scarce. This position is no exception and because it looks so simple, the solution can't be complicated either. Your tasks:
1. White to move and win
2. What tactical element was used to find the solution?
Total available points for this puzzle is 15. The answers will be published next week together with puzzle #81.

Puzzle #79 solution:
Last week I gave only one task, waiting with interest to see who got into the habit of explaining what they are doing week after week. Those who did it and explained their solutions, got bonus points! The other ones who did not, need to work more in this area of the game until it becomes something they need to do without anyone telling them to... Rick has the floor again:
"Brief position evaluation: Black is indeed ahead by two pawns in the endgame, but they are isolated and doubled in a terrible mess. White's passed pawn is the most far advanced, and will probably promote first. Black has to watch out for skewers or unusual checkmates, as White uses his Queen very actively.
1.Qe4+ ... This move stops the Black King from escaping to the "f-" file and out of harm.
1... Kh5 2.Qh7+ Qh6 (2... Kg4?? 3.Qh3+ ... 1-0) 3.Qf5!! ... A hard to spot move that shuts black down, since black can only play...
3... c5 Other moves lose on the spot: 3... g6 4.Qh3#) 3... Kh4 4.Qh3#) 3... Qh8 4.Qh3+) 3... Qg6 4.Qh3#) It's really funny how any move Black makes except "c5", all lose to "Qh3".
4.e6! ... Once again, the Black Queen can't come out because the sixth rank is closed. The fatal "Qh3" has the same effect here, so Black has to play...
4... c4 Black looks pretty foolish- it seems like he's trying to promote the "c-" pawn!! It's too bad White's about to ruin everything.
5.e7! ... Should Black play "Qh8"? How about "Qg6"? Nope; "Qh3" beats all! There's only one other move that might save the game.
5... Qc6+ Checking the White King and covering the "e-" pawns' promoting square is still not enough to stop White's invincibility!
6.Qf3+ ... If Black doesn't exchange Queens now, White will take the Black Queen for free. Black will soon realize that his position is hopeless.
6... Qxf3+ 7.Kxf3 c3 8.e8Q+ 1-0 Black probably despises the h3 square by now!"

Correct solutions:
Joshua, Jeremy - 10 + 5 bonus = 15 points
Rick - 9 + 5 bonus = 14 points
Owen - 10 points
Andy Q - 8 points
Wilson - 4 points
Andy Q - 20 points for puzzle #78

STANDINGS

Andy Q - 77 points
Joshua - 71 points
Rick - 52 points
Karl - 39 points
Wilson - 38 points
Alex Ge - 27 points
James - 23 points
Katerina, Andy Y - 20 points
Marcus - 19 points
Nathaniel - 18 points
Jeremy - 15 points
Owen - 10 points

Comment: 

Pinning in&nbspendgame