A WXYZ-Wing is a bigger wing: four related cells whose candidates together use only four digits, with a common digit that every arrangement forces.
Before this: Learn Y-Wing / XYZ-Wing first.
Why it works
Like Y-Wing and XYZ-Wing, you list the possible ways the wing can be filled. Every legal filling places the common digit Z somewhere in the pattern.
Cells that see every possible Z location get stung no matter which filling is true — so they cannot be Z.
Demonstration
Find four related cells locked to four digits as a wing group.
The green cells form a WXYZ-Wing. The common digit is 3.
Every possible filling of the wing places 3 somewhere in the pattern — check each world.
Eliminate 3 from cells that see every Z option (red).
Example 1
Scan for a four-cell wing locked to four digits.
This WXYZ-Wing forces 1.
Remove 1 from the common-see cells (red). Every filling places that digit in the wing.
Example 2
Scan for a four-cell wing locked to four digits.
This WXYZ-Wing forces 4.
Remove 4 from the common-see cells (red). Every filling places that digit in the wing.