Earn a percent of cash kept on hand at the end of wave.
Consists of both labs and workshop:
| ‣ | Type | Description | Unlock Cost | Max Level | Max Enhancement | Upgrade Costs |
|---|---|---|---|---|---|---|
| ‣+ | ‣ | Applier a multiplier to ‣, ‣, Interest and Max Interest. Starts at 1x and increases by 0.01x per level. | Free (after ‣ are researched) | 300 | 4x bonus | See Wiki for level costs. |
https://the-tower-idle-tower-defense.fandom.com/wiki/Interest#Overview