Bosses
Summon each boss, and what beating it opens.
Bosses never spawn on their own. You summon each one when you are ready. Four bosses form the main progression: each one's reward is what lets you reach, or build, the next. Two more live in the desert and cold regions; they are optional, and each drops a strong charm.
Summoning
The four progression bosses are summoned with a Call, an item you craft from what the layer you are in drops.
- Hold the Call and left-click where you want the boss to appear. There must be room for it there; if there is not, nothing happens and the Call is kept.
- The Call is used up when the boss appears.
- Fight on ground you have prepared: a wide, flat room, light, and a way to heal. See Fighting back and Gearing up.
If everyone moves about 2000 cells away, the boss leaves and the Call is given back. That is not a win and not a loss; you can summon it again.
Playing with friends makes bosses tougher: a boss has 1.5, 2 or 2.5 times its health with two, three or four players nearby when it appears. Its damage does not change.
Every boss has a sigil, a charm that it always drops alongside its main reward.
The progression
| Boss | Call | Made at | Main drop | What it opens |
|---|---|---|---|---|
| Brood Mother | 12 Chitin, 6 Iron, 4 Bronze | Anvil | Forge Core | The seal into layer 2 |
| Widow | 16 Ichor, 8 Steel, 4 Gold | Assembly Table | 2 Silk Glands | The seal into layer 3 |
| The Censer | 24 Cinder Hearts, 8 Tungsten, 12 Brimstone | Blast Furnace | 4 Pyre Cores | The final armour and the last fight |
| The Effigy | 1 Pyre Core, 24 Tungsten, 32 Brimstone | Assembly Table | Ascent Core | The rocket, and the end of the game |
1. The Brood Mother
The boss of layer 1. Collect Chitin from layer 1 creatures, smelt iron, and alloy copper with tin into bronze, then make the Brood Call at the Anvil.
Beating her the first time opens the floor between layer 1 and layer 2. Her Forge Core builds the Blast Furnace, the station for steel, titanium and tungsten tools and armour. She also drops the Forge Sigil.
2. The Widow
The boss of layer 2. Layer 2 creatures drop Ichor, and gold is found only in layer 2. Make the Widow Call at the Assembly Table.
Beating her the first time opens the floor into layer 3. She drops two Silk Glands and the Silk Sigil.
3. The Censer
The boss of layer 3. Layer 3 creatures drop Cinder Hearts; tungsten and brimstone are found there too. Tungsten melts only in a coke fire: see Making coke. Make the Censer Call at the Blast Furnace.
The Censer drops four Pyre Cores and the Pyre Sigil. Each piece of the final armour sets costs a Pyre Core, and so does the Effigy Call, so one win pays for a full set and the last fight.
4. The Effigy
The final boss. Make the Effigy Call at the Assembly Table from a Pyre Core and a large load of layer 3 materials.
The Effigy drops the Ascent Core, the heart of the rocket that ends the game, and the Ascent Sigil. See Leaving for building the rocket.
The regional bosses
Neither needs an item. Each sleeps in a machine inside its structure: walk up to it and right-click. Nothing is used up, and you can summon it again whenever you like. Only one of each can be awake at a time.
- Sun Warden: right-click the Sun Engine in the central hall of the desert pyramid. Drops the Sun Disc, which adds damage and shortens the delay between shots. See The pyramid.
- Hoarfrost Wyrm: right-click the Frost Engine at the top of the frost temple, in the cold region. Drops the Wyrmplate, which adds armour, softens contact damage and slowly restores health. See The frost temple.
The shop
The wandering merchant near your starting point sells more as you win: new stock opens after the Brood Mother, after the Widow, and after the Censer.
Next
Going down covers what to bring to each layer.