|Black to move|
2k2b1r/1pp3p1/p1p3qp/4Pn2/N4Bb1/1P1r1N2/P3QPPP/R4R1K b - - 0 1
d2, g2 protect f3
1. ... Bxf3 seems a double attack on Q and M#1, but gxf3 gets rid of the attacker which can cover h1.
cue: Nd4 is the way to add to the superior force against f3 with tempo (double attack)
cue: importance of keeping an attacker for the LoA f3-h1
In general: a piece that is B.A.D. can be encircled by harassing a defender or by adding an extra piece to the attack with tempo (which means a duplo attack)