Expert map

Glacial Trail

Info

Glacial Trail is an Expert map added in version 40.0 in December 2023, the same update that brought Corvus. It is set on a glacier full of icicles. Unusually for an Expert map, it has a single lane with one entrance and one exit, and the track winds through two loops. At around 20.6 seconds for a red bloon, it is one of the longer tracks in the Expert category.

The snowstorm mechanic

What makes Glacial Trail an Expert map is its recurring snowstorm. Every tower freezes for two rounds, once every ten rounds, counted from the round it was placed. A tower placed on round 1 is frozen on rounds 10 and 11, then 20 and 21, and so on. The floating ice cube with a monkey and the number "10" inside it is the in-game hint.

While frozen, a tower:

does not attack and cannot use or continue abilities (running abilities pause until it thaws);
cannot be selected, so you cannot upgrade or sell it;
still gives passive buffs, so Villages keep working;
still earns end-of-round cash if it is Benjamin or a Merchantman, while Banana Farms stop producing (Monkey Banks keep filling but cannot be collected).

Heli Pilots are stuck in place, Monkey Aces keep flying but stop shooting, and Etienne's drones and Geraldo's items freeze with their hero even though they do not look frozen. Ice Monkeys and Silas are immune.

Space and obstacles

Placement is very tight. Most open land is isolated snowy cliffs surrounded by icicles that block line of sight, plus ice sheets with poor views of the path. There is a small patch of water in the bottom-left for Subs and Buccaneers, but it sits low and has limited vision. The bottom-right glacier fits a Village or Alchemist next to one tower near the track. There are no removable objects.

How it compares

On paper it plays like a single-lane Advanced map, and normal single-lane defences work. The real difficulty is that no tower is reliable all the time. Compared to Workshop, the other big single-lane Expert map, Glacial Trail's path is simple, but the freezes force you to build a defence with backups. Like other Expert maps, it unlocks after you have won on 20 different maps.

How to beat Glacial Trail

Why this map is hard

The track itself is friendly: one lane, two loops, a decent length. The problem is the snowstorm. Every tower you own will be frozen for two rounds out of every ten, and you cannot do anything about it. If your whole defence relies on one tower or one hero, there will be rounds where it simply stops. The second problem is space: the good spots near the track are few, and many of them are surrounded by icicles that block line of sight.

The solution is planning. Spread out when you place towers, so their freeze windows do not overlap, and always have a second damage source covering the same job. Ice Monkeys and Silas are immune, which makes them the backbone of many strategies.

How to plan around the freezes

A tower is frozen on two rounds out of every ten, starting from when you placed it. Placed on round 1, it is frozen on rounds 10 and 11, 20 and 21, and so on.
Shift your placements: if your main tower was placed on round 3, place its backup on round 7 or 8 so they are never frozen together. Placing a tower mid-round is fine if it helps the timing.
Plan for the finale. By that same rhythm, a tower placed on a round ending in 2 to 7 will be active on rounds 98, 99 and 100. Towers placed on rounds ending in 8, 9, 0 or 1 will be frozen for at least one of them.
Do your upgrades and sales before a tower's freeze starts, since you cannot select it while it is frozen.
Perma-Spike spikes last for several rounds, longer than a freeze, so a Spike Factory with at least Deadly Spikes (tier 4 bottom) keeps protecting the exit even while the factory itself is frozen.

Best towers

Ice Monkey: immune to the snowstorm. Icicle Impale (x-x-5) can carry a huge part of the game with camo and white-bloon support, but it is not enough against the BAD on its own. Cheaper Ice Monkeys are a reliable slow that never turns off.
Heli Pilot: excels on a single lane with limited land. A 2-0-4 Comanche Defense or 5-0-2 Apache Prime is strong, but do not make it your only damage, since it will freeze. Note that a frozen Heli stays where it is and frozen MOAB Shove does nothing.
Mortar Monkey: works from anywhere and the outer areas suit it well. A 2-0-4 or 0-2-4 Mortar adds dependable area damage.
Dart Monkey (Spike-o-pult and Juggernaut): placed at the end of the second loop, its balls bounce off the icicles and hit many times. They are cheap enough to build two with different freeze timings.
Spike Factory: a Deadly Spikes or Perma-Spike factory at the exit keeps working through freezes thanks to long-lasting spikes.
Mermonkey (0-4-x Arctic Knight): an Arctic Knight placed on the ice cube under the entrance cannot reach the track with its main attack, but its ability aimed at the first loop wipes out blimps, which is very useful from round 90 onwards.
Monkey Village and Alchemist: the bottom-right glacier fits one of them next to a tower by the track. Villages keep buffing while frozen.

Best heroes

Silas: immune to the snowstorm, so he is always working. He pairs naturally with an Ice Monkey defence.
Sauda: there is a tight curve where she can hit bloons over and over. Just remember she freezes too, and plan a backup for her frozen rounds.
Benjamin: for Impoppable and farming runs. He keeps earning cash while frozen, although his abilities cannot be used during a freeze.

Easy and Medium

Use a standard single-lane build, but stagger it. For example: Sauda or a Dart Monkey at the tight curve on round 1, a second damage tower a few rounds later, then a Heli Pilot and a Mortar for coverage. Add an Ice Monkey early, since it never freezes. Camo for round 24 and lead popping for round 28 are needed as usual, and make sure each is covered by at least two towers placed on different rounds.

Hard

For Hard, build an Icicle Impale or a strong Ice Monkey group as the frozen-proof core, plus a Heli or Mortar setup and a Juggernaut at the end of the second loop. Check your freeze windows before rounds 76, 78 and 80, and if needed place an extra tower a couple of rounds before so something fresh is active.

CHIMPS

A typical approach combines immune towers with staggered damage:

Rounds 1 to 6: start with Sauda (or a Dart Monkey) at the tight curve on round 1. She will be frozen on rounds 10 and 11, so plan around that.
Rounds 5 to 9: add a second damage tower, such as a Dart heading to Spike-o-pult at the end of the second loop, so it covers rounds 10 and 11.
Rounds 10 to 24: add an Ice Monkey and start a Heli Pilot. Get camo detection on two towers with different timings before round 24.
Rounds 24 to 40: Spike-o-pult to Juggernaut, Heli towards 2-0-4 Comanche Defense, lead popping before round 28. Have blimp damage ready for round 40 that is not frozen that round.
Rounds 40 to 70: start a Spike Factory towards Deadly Spikes at the exit, and put a Village on the bottom-right glacier. Build towards Icicle Impale with camo support.
Rounds 70 to 90: Perma-Spike at the exit, Apache Prime or a second Comanche, and an Arctic Knight on the ice cube for blimp rounds.
Rounds 90 to 100: check which towers are frozen on 98, 99 and 100 and place a fresh damage tower on an earlier round if needed. Icicle Impale will not kill the BAD alone, so make sure a strong damage tower is active on round 100.

Impoppable

Impoppable allows Monkey Banks, which keep generating during freezes. Benjamin is also a good pick. The rest of the CHIMPS plan applies. See our Impoppable guide.

Dangerous rounds on this map

Any round where your main tower is frozen: this is the real danger. Know your freeze windows.
Round 24: one camo green.
Round 28: six leads.
Round 40: the first MOAB.
Rounds 63 and 76: ceramic rushes.
Round 78: rainbows, ceramics, a BFB and camo ceramics.
Round 90: camo regrow fortified leads and three DDTs.
Rounds 95, 98 and 99: DDTs and fortified blimps.
Round 100: the BAD, which needs single-target damage that is not frozen.

Video guides for Glacial Trail are on the BTD6 Master YouTube channel.

Frequently asked questions

How does freezing work on Glacial Trail?

Each tower is frozen for two rounds every ten rounds, counted from when it was placed. A tower placed on round 1 is frozen on rounds 10 and 11, 20 and 21, and so on.

Which towers do not freeze on Glacial Trail?

Ice Monkeys and the hero Silas are immune to the snowstorm.

Can I upgrade a frozen tower?

No. Frozen towers cannot be selected, so upgrade or sell them before their freeze begins.

How do you beat Glacial Trail CHIMPS?

Stagger your placements so key towers never freeze together, build a frozen-proof core of Ice Monkeys or Silas, and back it up with Helis, Mortars, Juggernauts and a Perma-Spike at the exit.