In three lines the digit's places fall inside the same three columns → erase it from the rest of those columns.
Technique 13 in the order the hint searches · difficulty Expert · up to advanced techniques
Where X-Wing was two lines and two columns, this is three and three. If the places a 6 can go across three rows all lie within the same three columns, those three rows take the three columns one apiece.
Collect only the lines with three places or fewer
Here is where it differs from X-Wing: the three lines need not each have all three places. One line may have two and another three; what matters is that together they union to exactly three columns. That is what makes it so much harder to spot by eye.
How the hint says it
In rows 3, 6 and 9, every place 6 could go lies within columns 2, 3 and 4. The three rows take one column each, so 6 comes off the remaining cells of those three.
Three lines use up all three columns
Each of the three rows takes one 6, and the only places for them lie within those three columns. Once the three columns have taken a 6 each, they are full, so no other cell in those columns can hold a 6.
The last technique the hint knows. Across 2,000 generated puzzles the times it was the deciding move can be counted on one hand — finding four seeds for the practice list took 30 seconds of searching.
Puzzles that need this technique
Four puzzles with a spot where nothing moves until you use Swordfish. Press a number to play it.
- Practice 1 ·
4-6558918 - Practice 2 ·
4-7607136 - Practice 3 ·
4-3009752 - Practice 4 ·
4-2453272