Puzzle of the week #365

Level: 
3-Bishop
Chess Diagram: 

[Event "Puzzle #365"][Date "2019.03.24"][Result "0-1"][SetUp "1"][FEN "5rk1/p2Rb3/1q2p3/1p3pr1/4B1nQ/2P3P1/PP3P1P/5RK1 b - - 0 1"]

The position has reached a boiling point. Each side is looking for the decisive combination: white is attacking the e7-Bishop with its last move (Rd1-d7), while black must find a way to blow up white's defence. Your tasks:
a) What is the e7-Bishop doing?
b) What square is black looking at to blow up white's defence and why?
c) Black to move and win

Total available points for this puzzle is 20. The answers will be published next time together with puzzle #366.

Puzzle #364 solution:
Polugaevsky - Gulko, USSR. This week's best answers are by the top scorers:

[Event "Puzzle #364"][Date "2019.03.10"][Result "1-0"][SetUp "1"][FEN "4r1k1/p1p2p2/1p2nPpQ/5q1p/3pN2P/P2P4/1P3PP1/4R1K1 w - - 0 1"]1. Nd6 (1. Ng5 Qxf6 2. Qh7+ Kf8 {White's Queen is trapped}) 1... cxd6 2. Rxe6 Qxe6 3. Qg7#

Correct solutions:
Glyn, Joey, Zhengyu, Walter, Matthew, Eric - 25 points
Aiden - 22 points
Coby - 20 points
Mengbai, Blake - 16 points
Brian, Lucas - 7 points

Standings:
Aiden - 124 points
Matthew - 120 points
Zhengyu - 108 points
Eric - 101 points
Walter - 95 points
Coby - 92 points
Joey - 85 points
Glyn - 72 points
Lucas - 66 points
Brian - 65 points
Mengbai - 62 points
Blake - 61 points
Lyvia - 45 points

Comment: 

Smothered mate