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An X-ray is a tactic whereas one pieces interacts with another piece going through an opposing foe, hence the term X-ray. Your opponent can often miss this tactic in their calculations, so discovering this can be a worthwhile profit.


An X-ray attack (Skewer) is where a ranged piece hits a valuable enemy and the piece behind it. The piece in front is forced to move away and the piece behind can be taken.

An X-ray defense is where a ranged piece defends a friendly piece through the attacking hostile piece. The bishop defends the knight from the queen. White should not go 1. Qxh8?? because then the queen will no longer block the bishop's view of the knight when she captures.

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8 a8 b8 kl c8 d8 nl e8 f8 g8 h8 nd 8
7 a7 b7 c7 d7 e7 f7 g7 h7 pl 7
6 a6 b6 c6 d6 pl e6 f6 g6 pl h6 6
5 a5 b5 pl c5 d5 e5 ql f5 g5 h5 5
4 a4 pl b4 c4 d4 e4 f4 g4 pl h4 pd 4
3 a3 pd b3 c3 bd d3 e3 f3 g3 pd h3 3
2 a2 b2 pd c2 d2 e2 f2 g2 h2 2
1 a1 b1 kd c1 d1 e1 f1 rd g1 h1 1
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The bishop defends the knight from the white queen.