How to solve an XYZ-Wing in Sudoku
An XYZ-Wing is a three-candidate pivot with two wings, which removes a digit from cells that see all three cells.
How it works
The pivot holds X, Y and Z. One wing holds X and Z, and the other holds Y and Z. Both wings are seen by the pivot.
Whatever the pivot becomes, one of the three cells has to be Z. So a cell that sees all three cannot be Z.
How to spot it
It is an XY-Wing whose pivot also contains the shared digit. The cells that can be cleared are few, since they must see the pivot and both wings.
A worked example
This is a step from a real puzzle, a moment where the next move needs an XYZ-Wing.
P is the pivot, W are its two wings. Struck-through digits are the ones that can be removed.
R6C9 holds 2/4/8, linked to R6C4 and R5C9. Whichever way it resolves, one of these three cells must be 8, so remove 8 from cells that see all three: R6C7.
Where it fits in Rocksled Sudoku
Puzzles that need an XYZ-Wing are never rated below Expert. Each step of this kind adds 66 points to a puzzle’s difficulty score. When you ask for a hint that needs it, the game names the technique and shows the cells involved. See how to play for the rest of the controls.