Sue de Coq
Count the digits across a line-box crossing and the two groups of cells leading out of it, and remove the candidates that fit nowhere.
How it works on this board
The intersection's candidates split exactly between a box set and a line set
5
9
2
8
8
1
2
9
2
3
6
9
8
4
5
6
3
1
7
2
6
7
6
4
4
5
2
3
2
5
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