Hint: Words using these letters: brittle
The answer to this puzzle is:
1. LITTER
2. BITTER
3. TRIBE
4. TITLE
5. LITER
6. LITE
7. RITE
8. TILT
9. TILE
10. BELT
11. BET
12. BIT
13. BIT
2. BITTER
3. TRIBE
4. TITLE
5. LITER
6. LITE
7. RITE
8. TILT
9. TILE
10. BELT
11. BET
12. BIT
13. BIT