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Glacieradon Guide — Zombie Invasion Alliance Boss

Alliance · 2026-10-14

What Is Glacieradon?

Glacieradon is the alliance boss that sits on top of the Zombie Invasion event. When it is active the event is named Zombie Invasion - Glacieradon in the event list, and the usual zombie-farming event gains a second layer: your alliance can summon and kill a giant ice beast for a separate set of rewards.

It is not an extra event with its own schedule. It is part of Zombie Invasion, and it only appears in the runs where the beast is included.

One Challenge, One Button, One Hour

Each alliance gets exactly one Glacieradon challenge per event, it has to be started by hand, and only the leader or an R4 can start it. This is the single biggest reason alliances get nothing from it. The bar fills, nobody presses the button, and the beast leaves. Decide in advance who starts it and when.

When It Appears

Season 2's panel lists the unlock as Tempest Beast on day 57, with the note that it awakens Glacieradon. From that point it is part of the game's recurring event rotation rather than a one-off piece of season content — which is why it also turns up between seasons.

Do not confuse it with two things that share the name:

Zombie SiegeA completely separate alliance event. Waves of zombies attack every member's base. Nothing to do with Glacieradon
Season 2 Nuclear FurnaceThe Season 2 warzone event also features Glacieradons — four of them, marching across the map at the Nuclear Furnace. Same creature, different event, different rules

How the Challenge Is Unlocked

The gate is Zombie Bosses, not zombies.

  1. Kill invading zombies on the world map. These pay Courage Medals, which you spend in the event shop. They do not fill the Glacieradon bar.
  2. Zombie Bosses have a small chance to appear after a zombie kill. They are strong enough to need a rally.
  3. Defeating Zombie Bosses earns Glacieradon progress points for your alliance. This is the only thing that fills the bar.
  4. Once the bar is full, the leader or an R4 triggers the challenge manually.

So the alliance's job in the first half of the event is to find and rally Zombie Bosses, not to grind ordinary zombies. Players farming zombies flat out for Courage Medals are earning for themselves and contributing nothing towards the beast.

The Fight

Once an officer starts the challenge, Glacieradon spawns and a clock starts.

RuleDetail
Challenge length60 minutes. If its HP is not at 0 when the hour is up, it escapes
Attacks per player30, for the whole event — not 30 per day and not 30 per challenge
CritsAny successful attack can crit for several times its normal damage. Crit attacks also pay multiplied rewards
Ice attacksGlacieradon freezes commander bases. A frozen base cannot relocate or rally until it thaws
Other alliancesYou cannot attack Glacieradon while another alliance is challenging it

The freeze is the mechanic people get caught by

Rallying is how most alliances handle every other boss in the game. Glacieradon's ice attack takes exactly that away — a frozen base can neither rally nor relocate. Plan around members dropping out of the rotation mid-fight rather than assuming everyone can act for the full hour.

The Clock That Actually Matters

Glacieradon Leaves Two Hours Early

Glacieradon departs 2 hours before the event ends, and no challenge can be started after that. The deadline for starting is not the end of the event — it is two hours before it. An alliance that plans to "do it on the last evening" can find the button already dead.

Work backwards from that. The challenge takes an hour, so the last useful start is three hours before the event ends, and even that assumes a full turnout. Pick a slot when most of the alliance is awake and online, and announce it.

Rewards

  • Every successful attack pays an attack reward, and a crit multiplies it.
  • The final blow pays 10x. If the killing blow is itself a x2 crit, it pays 12x — the crit's x2 is added to the 10x rather than multiplied by it, so the most a final blow can pay is 12x, not 20x.
  • Glacieradon's Treasure drops when it dies. Collect it from the map for a large reward.
  • Kill it and every alliance member gets a reward mail. Fail and everyone still gets a participation reward. Each player collects that mail once per event.

Nobody is punished for taking part, so there is no reason to hold attacks back. The only thing a saved attack does is make the kill less likely.

Two reward rules worth knowing

24-hour join ruleNew alliance members cannot collect Glacieradon's Treasure within 24 hours of joining. Recruit ahead of the event, not on the day
Other alliances' treasureYou cannot claim the treasure dropped by another alliance's Glacieradon

If that 24-hour rule sounds familiar, it is the same family of trap as the 48-hour rule in the Zombie Siege guide — joining an alliance the day of an event routinely costs the new member the rewards they joined for.

Your Squad Does Not Matter. At All.

This is the part that surprises people, and it is measured, not guessed.

Glacieradon's HP is a counter, not a damage pool. Through Season 4 it has around 1,000 HP — more from Season 5 onwards, as below — and a winning attack takes off exactly 1. The game then rolls its own critical hit, which multiplies that to 2, 3 or 5. The battle report says so in as many words: "This attack dealt 1 damage", or "a critical hit of 3 damage".

Read that again, because it is the whole event. The number in the report is a single digit. It is not your squad's damage, scaled down — your squad's damage is not in the calculation anywhere.

So:

PowerIrrelevant above the win threshold. A squad at a fraction of another's power takes exactly the same off the counter
Troop typeIrrelevant. Tank, Missile, Aircraft and mixed formations all behave identically — Glacieradon has no weakness to exploit
Critical hitsThe event's, not yours. Nothing about your squad makes a crit more likely or larger
Winning the fightThe only thing that matters — and squads well under the beast's own power still win it

Checking that properly meant attacking with squads from well below Glacieradon's own power up to several times it, across every troop type, and the base damage never once moved.

Do Not Bring Your Wanted Boss Squad

The Wanted and Rampage bosses pay +50% to one hero type, so the right squad there is built around that weakness. Glacieradon has none. A squad shaped for the Wanted Boss gives up the mono-type formation bonus to chase a bonus that does not exist here. Bring whatever reliably wins — and since all casualties are light injuries with zero deaths, "reliably wins" is a low bar.

The crit is what pays, and the loot follows it exactly

Every attack pays medals, iron, food and coins — and the payout scales strictly in proportion to the damage number. A x3 crit pays three times a normal hit; a x5 pays five times. Not five times the HP removed and the same loot: five times everything.

That is why the crit matters so much more here than the fight does. A single x5 is worth five ordinary attacks, and no amount of squad investment buys you one.

You have no control over that roll, which is rather the point: the only thing you control is how many attacks you get in.

Speed Beats Everything

Here is the thing that should change how your alliance plays it. An active alliance strips Glacieradon's HP at something like ten points a second. A thousand-point pool does not survive that for long.

It is given 60 minutes. It can be dead inside two.

The consequence is blunt: you have 30 attacks and you will not get to spend them. Expect to land a handful before it is already nearly down — and expect anyone who arrives late to get nothing at all.

Being There Beats Being Strong

The loot goes to whoever is tapping in the first two minutes. A maxed account that logs in five minutes after the officer starts the challenge earns less than a weak account that was already sitting on the screen. Announce the start time, and have people waiting on it.

Two things follow:

  • Use all your marches. Each attack is a march. Rotating through all four squads lets you keep several attacks in flight instead of waiting for one to come home — which is exactly why it does not matter that your fourth squad is weak.
  • Do not spend time optimising a squad. Every second spent in the formation screen is an attack you did not make.

What We Still Do Not Know

  • Whether a higher-level Glacieradon exists. Everything above was measured at the one we have seen. The event does scale by season — it carries more HP and a worse critical-hit rate from Season 5 onwards, which roughly doubles the attacks needed — but we have not seen a harder version within a single season.
  • The critical-hit rate. We have far too small a sample to publish a figure, and it is not shown in game.
  • The progress points needed to summon it, and how many each Zombie Boss level pays. Not stated anywhere a player can see.
  • What a lost battle does. Every attack we recorded was a win, so "win the fight" is an assumption, not a measurement. It is a safe one — but do not read it as proof you can send anything at all.

Officer Checklist

  1. Before the event — recruit, so new members clear the 24-hour treasure rule.
  2. Early in the event — push the alliance onto Zombie Bosses, with rallies, not solo zombie farming.
  3. Pick the start slot — peak online hours, announced in advance, and at least three hours before the event ends. Tell people to be on the screen, not merely online.
  4. Start it yourself — leader or R4 only, and the alliance gets one attempt.
  5. During the fight — everyone attacks immediately, with every march. It will be over in minutes, not the hour it is given.

Common Mistakes

  • Waiting for the bar to start it. It never does. The challenge is manual.
  • Leaving it to the final hours. The beast leaves 2 hours before the event ends.
  • Farming zombies instead of Zombie Bosses. Medals are yours; only bosses fill the alliance bar.
  • Saving attacks. There is no second challenge to save them for — and it dies long before you reach 30.
  • Bringing the Wanted Boss squad. Its +50% does not apply here, and the formation costs you more than it earns.
  • Turning up late. The fight can be over inside two minutes. Late is the same as absent.
  • Recruiting on the day and expecting the new members to collect treasure.