Frozen Bloons grow sharp icicles that can pop Bloons that touch them.
~ In-game Description
Icicles 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.
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.
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.
Icicles has been buffed overall since it was first released. Just like with Cryo Cannon, its previous upgrade, Ninja Kiwi had made them both stronger at damage, with intention of transforming them into hybrid damage + freeze towers.
Icicles blast radius pierce increased (20 → 30)
While Icicles is quite fun for midgame cleanup, we acknowledge points raised on Cryo Cannon trading off its freeze prowess too quickly when the smaller freeze area even with such a fast rate increase still overall makes it struggle to slow as effectively. To counter this a little we have doubled the freeze radius of Cryo Cannon, but also increased damage of both the Ice Balls & Icicles to highlight more the intention of this path swapping to a damage hybrid earlier.
~ Ninja Kiwi
Ice ball damage increased (1 → 2)
Icicles 'shard' damage increased (1 → 2)
Blast radius (correctly) increased from 10 to 20, from the Cryo Cannon buff
[undocumented] Icicles can now apply shards onto White and Zebra Bloons but not freeze or damage them with the ice blasts
[undocumented] 2-0-4 Icicles shards now pop Lead Bloons.
Frozen Green Bloon with icicles
Many bloons in a clump affected by Icicles
Crosspathing in BTD6 (top path 1, bottom path 2)
Icicles applying onto White Bloons (Version 25.0 undescribed change)
Creating ice blasts onto groups of bloons, with some Whites left intact with the status effect
Icicles upgrade icon
Icicles as seen in the BTD6 start screen
Icicles spikes (without bloon)
Icicles Version 25.0
Icicles demonstration on Version 25.0. Damage types are demonstrated.
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.