6-cell Kakuro run summing to 23

Only 2 digit sets sum to 23 across 6 cells. That makes this run useful for cross-reference deductions: a digit you can rule out from one of the cells (because the perpendicular run forbids it) often forces the entire combination.

Locked digits: 1, 2, 3, 4. These digits each appear in every valid combination, so they each must occupy one cell of the run; useful when a perpendicular run rules any of them out of a candidate cell.

Forbidden digits: 9. None of this digit appears in any valid combination, so you can rule it out of the run's cells immediately.