Puzzle of the week #268

Level: 
3-Bishop
Chess Diagram: 

[Event "Puzzle #268"][Date "2015.01.27"][Result "0-1"][SetUp "1"][FEN "rq3rk1/pb1p1ppp/1p2p3/2b1n3/2P1P3/2NB2P1/PP1Q1PP1/RN3RK1 b - - 0 1"]

The most dangerous weapon a player has is not his Queen, but the element of surprise! When you take the opponent by surprise, you don't need to use a very fancy or complicated piece of tactics to win. Look at our current position: black has the Queen and remaining light pieces pointing toward white's castle, as well as the pin on the f2-pawn; however this can't be enough for a quick win, can it? At least this is what white thought. It is black to move; your tasks:
a) What kind of pin is this?
b) Use the pin to win the game for black

Total available points for this puzzle is 20. The answers will be published next time together with puzzle #269.

Puzzle #267 solution:
Game Blackburne - Day, Derby 1876. Thank you all who annotated the game! You all get full points for the effort. Of course each one of you had written different things, as you are different individuals; what matters is that you made an effort to think about it and write it down. It is the main purpose of the puzzle and you have achieved it.

[Event "Puzzle #267"][Date "2014.12.17"][Result "1-0"]1.e4 e5 2.d4 exd4 3.c3 dxc3 4.Bc4 cxb2 5.Bxb2 Bb4+ 6.Nc3 d6? {See diagram} ({Better is} 6...Nf6) 7.Qb3! Bxc3+ 8.Bxc3 Qg5? (8...Kf8 {Defends the g7-pawn}) 9.Bxf7+ Kf8 10.Nf3 Qg4 (10...Qxg2 11.Rg1 Qh3 12.Bxg7+ Ke7 13.Bxh8 {White is winning}) 11.O-O Nh6 12.Bc4 Nc6 13.e5 {Opening the position} 13...dxe5 14.Nxe5 Nxe5 15.Bxe5 Qg5 16.Rfe1 Nf5 17.Bxc7 Bd7 18.Qb4+ Ne7 19.Rxe7 {Winning the Queen and soon after the game} Qxe7 20.Bd6 Qxd6 21.Qxd6+ Ke8 22.Re1+ Kd8 23.Re7 Kc8 24.Qxd7+ Kb8 25.Qxb7#

Correct solutions:
Benjamin, Cody, Terry, Coco, Bradley, Deryk - 25 points

Comment: 

Absolute pins