Nothing upsets me more in chess calculation than missing a candidate move.
Take the following tactical training position from Blokh's Combinations Motives.
I had looked at Rxh7, Nxe7, Nf6 and Qe4
See if you can solve the following.
Diagram 795: Difficulty 5, Black to Move
Why does this tactic work?
White's pieces are so aggressively place: Rh3 firing at h7, Qd3 cutting over to h7, The Knight at d5 eyeing e7 and f6
Admist all this, I failed to see the potential of the dark squared Bishop pointing at the Black King. I also underestimated the Rook at g1 lurking, waiting for the g-file to be opened