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A torchlit dungeon of stone halls and stairs, green slimes in one hall and a purple crystal on a dais in the lowest room.

World 3

The Undervault

Hold the vault

Unlocks when you clear stage 2 of The Forest's Siege.

A dungeon of halls and stairs deep under the keep, with the crystal in its lowest vault. Three lairs open onto it: the cistern's grate, the deep stair and the treasury, and their roads meet on the way down.

Build on the high ground over the roads, on the altar's dais, the galleries and the terraces round the hall's pit, out of reach of the enemy's blades, and in the rooms beside them, where only the doorways let it in.

Keep moving and keep the crystal shining.

Siege

Thirty waves over three stages, saved at the start of every wave. Each stage ends in a boss wave and the next brings tougher enemies. Stage 2 also opens a fourth skill slot and lets towers and skills reach level 5.

Casual
Weaker foes, fewer elites
Normal
The intended challenge
Extreme
Tougher foes, more elites

Enemies

Every wave has a boss, and each one drops a chest when it falls.

Slimes

  • Gel

    Swarm

    Small and quick, they swarm whatever is near. Oozes split into them.

  • Ooze

    Melee

    Slain, it splits into two Gels.

  • Spitter

    Ranged

    Spits acid at structures, which then take more damage for a while.

  • Gelatinous Cube

    Boss

    Pounces on the hero and swallows it for a moment. Slain, it splits into Oozes.

Constructs

  • Drone

    Swarm

    Old clockwork that comes in swarms, clawing at whatever is near.

  • Gunner

    Ranged

    Fires bursts at structures, then overheats: venting, it stands still and takes more damage.

  • Clanker

    Heavy

    Heavily armored. Slain, it bursts into scrap that hits the structures round it.

  • The Forgotten

    Boss

    Sweeps its eye's beam across a fan, hitting every structure and the hero in it.

Mimics

  • Coffer

    Runner

    A little mimic that hops past the fight for the crystal. Catch it before it gets there.

  • Mimic

    Melee

    Armored, and bites structures twice as hard.

  • Gilded Mimic

    Ranged

    Keeps its distance and spits coins at the hero. Step aside to dodge them.

  • Hoard King

    Boss

    Swallows a badly damaged structure whole. Slain, it showers coins.

Trials

Nine short runs, each with a rule of its own. Three start from a set-up board: a puzzle to solve. They open as you clear the Siege's stages, and each earns a title when you clear it on Extreme.

  1. Storm Front

    5 waves

    Only Storm Towers can be built.

    Title: Stormcaller, +10% skill damage

  2. High Ground

    5 waves

    Build only on the high ground over the roads.

    Title: Holdfast, +10 structure armor

  3. Slime Tide

    5 waves

    Only slimes, a Gelatinous Cube leading every wave.

    Title: Slimebane, +10% tower splash

  4. Garrison

    5 waves

    At most 6 structures. Raise them high.

    Title: Commander, -10% upgrade cost

  5. Silenced

    5 waves

    Your hero has no skills, only its attack.

    Title: Duelist, +10% attack damage

  6. Stampede

    5 waves

    Enemies move 25% faster.

    Title: Trapper, -5% enemy speed

  7. Overflow

    Waves 4–6 · Puzzle

    Oozes split under single shots. Rework the line.

    Title: Tidebreaker, +10% hero health

  8. Scrap Heap

    Waves 7–9 · Puzzle

    Clankers burst into scrap. Kill them on the road.

    Title: Ironclad, +10 hero armor

  9. King's Feast

    Waves 8–10 · Puzzle

    The Hoard King swallows the battered. Mend first.

    Title: Hoardbreaker, +20% wave rewards

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