Hydra Rocket Pods (BTD6)

"Shoots depleted bloontonium missiles that can damage all Bloon types and trigger multiple explosions."

- In-game description

Hydra Rocket Pods (also known as HRP or Hydra) is the Tier 3 upgrade of Path 2 for the Dartling Gunner in Bloons TD 6. Instead of darts, the Dartling Gunner now shoots deadly missiles that create multiple explosions per missile, which deal 1 damage per explosion to up to 6 bloons, with each explosion having a blast radius of ~12. Like the older Hydra Rocket Pods from BTD5, Hydra Rocket Pods automatically gains the normal damage type, allowing it to pop any bloon type, including Black Bloons.

Each missile by default creates 3 explosions on impact (4 explosions with Powerful Darts), similarly to Captain Churchill, with a very brief delay in between each explosion. Unlike any other explosive-based tower, the total number of explosions per missile can be increased with pierce buffs such as Berserker Brew, although every number of explosions consumes an amount of pierce for the missile projectile, rounded up. For instance, Berserker Brew's +2 pierce buff only adds +1 explosion, while Stronger Stimulant's and Permanent Brew's +3 pierce buff adds +2 explosions. The missile itself has 6 pierce, and each created explosion requires and uses 2 pierce.

It costs $4,465 on Easy, $5,250 on Medium, $5,670 on Hard, and $6,300 on Impoppable.

Summary
Hydra Rocket Pods excels at destroying grouped bloons by its ability to create multiple explosions per missile. Because of how the new explosions work, it acts similarly to Captain Churchill by producing up to 3 explosions on impact (or 4 with Powerful Darts), making it effective at handling multiple groups of bloons along straight lines.

Tips

 * 0-3-2 is better in terms of DPS. This is because giving it more pierce actually makes each rocket create more explosions akin to how Captain Churchill can gain extra explosions per shell as he levels up. Hydra Rocket Pod missiles produce one more explosion every time the missile itself gains more pierce.
 * 2-3-0 is more accurate, but it loses out on extra numbers of explosions per missile. Focused Firing is the main upgrade to go for when crosspathing with Path 1. Adding Laser Shock only affects the initial hit of the Hydra Rocket Pods, but it does not affect the missile explosions, which otherwise in theory would be the better crosspath.
 * With this upgrade, the Dartling Gunner with Hydra Rocket Pods turns into a fast-attacking Captain Churchill. As such, place it where Captain Churchill would be placed, but account for the inaccuracy too.
 * There is a special interaction with the Alchemist's buffs where the pierce buffs only gain one fewer extra explosions than usual number of pierce buff units (i.e. +1 explosion with Berserker Brew, and +2 with Stronger Stimulant or Permanent Brew). However, percentage pierce buffs from Homeland Defense double the number of total explosions.

Trivia

 * The lack of the Depleted Bloontonium Darts upgrade means that a 0-3-0 Hydra Rocket Pods is the cheapest possible Dartling Gunner that naturally can pop Lead.
 * 0-0-2 Dartling is the cheapest possible Dartling Gunner that naturally can pop Frozen, or 3-0-0 Laser Cannon before Powerful Darts was buffed to pop Frozen.
 * The artwork has a unique gas mask and helmet and is similar to the MS-06 Zaku II from the mecha anime series Mobile Suit Gundam.
 * The multiple explosion mechanic for the Hydra Rocket Pods in BTD6 is likely inspired by a bug in the mobile versions of BTD5 generation games whereby Hydra Rocket Pods projectiles gain +1 explosion when paired with pierce buffs such as Monkey Village's Monkey Fort upgrade. Interestingly enough, the bug still exists in BTD5 Mobile and BMC Mobile, but not in BTDB Mobile.
 * Hydra Rocket Pods is the only Tier 3 Dartling Gunner upgrade whose artwork features the monkey showing its belly button.
 * The sprites for the Hydra Rocket Pods explosions are likely reused sprites from activating the Vine Rupture ability from the respective MK Point.