Every wave in tiers 15-19 pays one column when it ends: the one for its kind.
What each wave pays
9| Item | Regular wave | Final wave | Big final wave |
|---|---|---|---|
 Scrap Metal | ×1 | ×2 | ×5 |
 Broken Glass | ×1 | ×2 | ×4 |
 All-Purpose Strengthener | ×1 | ×1 | ×1 |
 Fine Sheet Metal | ×1 | ×1 | ×1 |
 Instant Spicy Hotpot | ×1 | ×1 | ×1 |
 Inspirational Story | ×1 | ×1 | ×1 |
 Door Repair Kit | - | ×1 | - |
 Electronic Components | - | ×1 | ×2 |
 Tempered Glass | - | - | ×1 |