ALS-XZ
Expert Removes candidates Used in: Sudoku, Killer Sudoku
Two Almost Locked Sets are joined by a restricted common digit (X). That link forces a second shared digit (Z) into the sets, so Z can be removed from any cell that sees every Z candidate in both sets.
How to spot it
Two almost-locked sets joined by a restricted common digit.
What you can conclude
Eliminate the second shared digit from any cell that sees all of its candidates in both sets.
Worked example
Two almost-locked sets sharing a restricted 4 force a 7 into them; a cell that sees all their 7s cannot be 7.