Very nice! There can only be one tactic, but it works nicely
Impossible to see in blitz with White's threat Nxf5
That remembers me of the position after
1.d4 d5 2.Nf3 Bf5 3.Bf4 e6 4.e3 Nf6 5.c4 (diagram):
Black was thought to have an easy life after
5...Bxb1 6.Rxb1 (6.Qa4+ Qd7 is possible but not necessary) since
6...Bb4+ forces
7.Ke2, but White has some backlash, e.g. :
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7...dxc4 8.Qa4 Nc6 9.Ne5 asks for trouble after
9...a5 (or
9...Nd5) and the thematic
10.Nxc6 Qd7, Black regains the piece but likely not for free
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7...Be7 8.Qb3 Qc8 9.g4! with initiative
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7...Bd6 8.g3 Bxf4 9.gxf4 is likely Black's safer, but += by computer
So, not sure Black is threatening anything with this trick, maybe he should just play Bd6 instead of Bb4+ ?