Swordfish
Three rows whose homes for a digit occupy just three columns — the digit falls from those columns elsewhere.
How it works
- 1X-Wing one size up. Find three rows where a digit's remaining cells fall within the same three columns.
- 2Those three rows need three of that digit between them, and only those three columns can supply them.
- 3So the digit is impossible everywhere else in those three columns. Works with rows and columns swapped.