4-cell killer cage summing to 26

5 digit sets sum to 26 across 4 cells. Without other constraints this cage is loose; the value comes from pairing it with the cage's row, column, or box context — every digit ruled out elsewhere narrows which combinations remain.

Forbidden digits: 1. This digit never appears in this cage no matter which combination resolves; you can eliminate it from every cell of the cage as you pencil in candidates.