Excel Combine Columns Formula

I have several text-filled columns in Excel that need to be merged into a single, duplicate-free string—no commas, spaces, or other separators between the items. I want a rock-solid formula (no VBA this time) that:

• References a dynamic range so I can add or remove rows without editing the formula
• Ignores blank cells automatically
• Eliminates any repeated text, keeping the first occurrence only
• Returns the final result in one cell ready for downstream formulas or export

Please include a short explanation of how the formula works and a sample workbook that shows it in action on at least two different column counts. If a newer Excel function such as TEXTJOIN, UNIQUE, or LET makes the task easier, feel free to use it; otherwise, a traditional array formula is fine as long as it remains efficient.

I’ll consider the task complete when I can paste your formula into my own sheet, watch it expand or shrink with my data, and see a clean, concatenated string with all duplicates gone.