This upgrade costs $380 on Easy, $450 on Medium, $485 on Hard, and $540 on Impoppable.
Barbed Darts will produce more pierce potential overall compared to adding Twin Guns, but for the same cost it doesn't have as much early-game value in comparison. This is because a majority of the issues in early-game come from the faster bloons rather than grouped bloons. However, this upgrade can come in handy when extra dart pierce is necessary.
Mostly implemented crosspath interactions with non-dart attacks.
- Heat-Tipped Darts crosspath now gives submerged Bloontonium Reactors with extra pierce.
- Pierce bonus for submerged Bloontonium Reactors and Energizers decreased (+20% → additive +30; 84 → 70 for Reactors, and 1200 → 1030 for Energizers)
- Energizer pierce reduction is undocumented in Ninja Kiwi's Version 23.0 patch notes.