Daily Chess Improvement: Keen Eye Chess Tactic!

This was one of the puzzles I created for 2017 SPFGI

White to move. How should white proceed?

Comments
No. 1-3
DaveCubby
DaveCubby

3...Qa6 and White is completely lost.

2. Bb8+!! (better than 3. Nb5+?) 
CraigB
CraigB
  1. Qd4+ Bb6 2. Nb5+ ab 3. Qa1+ Ba5 4. Q:a5#
DaveCubby
DaveCubby
  1. Qd4+

a) 1...Kb8, 2. Qb6+! (Black Bishop pinned by White Bishop on h2) Qb7, 3. Qxb7#

b) 1...Bb6, 2. Bb8+!! Qxb8 (2...Kxb8, 3. Qxb6+ mating next move) 3. Nb5+! axb5, 4. Qa1+ Ba5 (forced), 5. Qxa5#

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