Icicles

"Frozen Bloons grow sharp icicles that can pop Bloons that touch them."

- In-game description

 is the Tier 4 upgrade on Path 3 for the Ice Monkey in Bloons TD 6. With this upgrade, any Bloons frozen by the Ice Monkey to grow icicles. These icicles deal two damage at any Bloon that touches them, and pierce up to 3 bloons. The icicle planted status effect lasts for up to ~2 seconds. Inheriting the properties of Cryo Cannon, its ice blasts deal 2 layers of damage too.

The icicles that form on bloons are considered the shatter type, allowing the popping of White Bloons, Zebra Bloons, and Frozen Bloons but not Lead Bloons unless given lead-popping of any method. Icicles are also grown on Bloons that Ice Monkey cannot normally freeze such as White and Zebra Bloons, but not Lead Bloons. Grown icicles can pop Leads if the originating tower had lead-popping by any source at the time of shooting a snowball.

It costs $2,335 on Easy, $2,750 on Medium, $2,970 on Hard, and $3,300 on Impoppable.

Summary
Icicles can be used to improve mid-game potential while saving up for an early Icicle Impale. It is best used as a cleanup option in combination with other towers. Combined with the powerful ice blasts and icicles, this tower can deal quite good chunk amount of damage to bloons overall.

Tips

 * Icicles is a cheap option to help control bloon rushes by dealing fair damage while freezing bloons.
 * The high bloon damage output of Icicle can be accompanied by a tower that deals a lot of MOAB damage but struggles against bloons, such as Arcane Spike or Dark Knight.
 * Icicles is also a good stepping stone to the powerful Icicle Impale.
 * Because of its good combined range, damage, and attack speed, 2-0-4 or 0-2-4 Icicles are both pretty good at handling Round 63 as long as it is paired with backup defense. Both crosspaths help beat Round 63 in their own right; 2-0-4 is oriented for popping the Leads and slowing down the densely clumped Ceramics, while 0-2-4 is better for purely dealing with the densely clumped Ceramics.
 * It is good to note that Icicles can pop White Bloons if there are other bloons it has previously applied Icicles on. This is mostly useful in player-made challenges.
 * Icicles can spawn on any type of non-lead bloon (unless with 2-0-4), including Whites and Zebras.
 * The 0-2-4 Icicles is superior for pure damage. Use 2-0-4 only if Leads need to be popped or if target priority micromanagement is necessary.
 * Compared to other mid-game options, Icicles doesn't fall off in the late-game to such a high extent compared to M.O.A.R. Glaives or Ring of Fire, but it still is shadowed by Bloon Impact and Spiked Balls when it comes to countering Super Ceramics.

Trivia

 * Prior to the Cryo Cannon price buff in Version 23.0, Icicles costed the same amount as Cryo Cannon, similarly to how Ice Shards costs the same as Absolute Zero in BTD5.
 * Despite what the patch notes mentioned regarding Cryo Cannon pierce not being affected by the change, Cryo Cannon and its subsequent upgrades actually received a pierce buff from 20 to 30. This also affects the Icicles upgrade.
 * The damage buffs to Icicles actually make it harder to complete One Ice Monkey Only plus 0-2-0 Village, rather than easier. This is because the blasts deal too much damage for the icicle stockpiles to become retained, not to mention that icicles cannot form if bloons are already popped.
 * However, the undocumented change in Version 25.0 that allows icicles to plant onto Whites and Zebras allows this to become possible again.