Crystalline Caverns

The Crystalline Caverns is a new dimension reachable via a crafted portal. Once inside, the left panel becomes a Stardew-style combat biome — you have a sword, there are mobs, they hit back. Drops from mobs land on the floor and auto-pickup when you walk over them.

The Caverns is also a 2nd campaign map on the right panel — a full 50-wave tower-defense track that tops out with the Prism Warden boss. You can pick it from the LEVEL dropdown on the Campaign screen just like Desolate Depths.

Getting there

The Caverns is always gated behind crafting the Crystalline Gateway. There is no auto-spawn; you craft it every run.

1. Research the crystal_attunement tech node on the tech tree.
2. Queue craft_crystalline_gateway at the Void Forge. Ingredients: 4 × crystal_core, 2 × steel, 3 × obsidian, 6 × glass. Craft time: 20s.
3. Collect the gateway bubble — your character enters placement mode exactly like a station: a purple ghost preview follows your cursor.
4. Click anywhere on the current level to drop the gateway. You can place it on the Surface, in the Cave, or even inside the Caverns — wherever fits your build. The preview persists across level changes, so you can carry it through an existing portal first if you like.
5. Walk into the gateway to teleport into the Crystalline Caverns.
6. To return, walk back through the same gateway.

In co-op, every placed gateway is shared — anyone in the party can use it.

The Caverns biome

The left panel renders a purple-tinted cavern grid with four node types and five mob types. You can harvest nodes the usual way, and fight mobs by clicking on them.

Harvest nodes

Node	Drops	Notes
Prism Cluster	Prism Shard	Quick to harvest
Resonant Node	Resonant Dust	Needed for Crystal Tuner
Geode Deposit	Geode Core	Thick shell — slow to break
Lumencore Deposit	Lumencore	Rare; foundational for T3 towers

Mobs

Mob	HP	Behavior
Crystal Sprite	25	Fast harasser. Darts in and out.
Resonance Wisp	18	Large aggro radius, low HP.
Geode Crawler	80	Armored — first hit per player does half damage.
Shard Hound	40	Pack aggro: wake one and its neighbors come too.
Prism Warden (miniboss)	600	Summons minions at HP thresholds. Rare.

Mob AI: idle wander near spawn → aggro inside their aggro radius → chase you until you leave a wide leash → attack on contact. Every mob drops crafting resources on death.

Combat

• Default weapon: Basic Sword (15 damage, 0.8s swing).
• Click a mob to set it as your attack target. Your character auto-walks into sword range and swings on cooldown.
• Contact with a mob damages your player HP. Out-of-combat HP regens at 1 HP/s after 3s without a hit.
• Death consequences:
  • Solo: the run ends immediately — TD_GAME_OVER fires with reason player_death.
  • Co-op: you respawn at your party's placed gateway (or at the Cave spawn if none exists). The run continues.

You can also equip a better sword from the Equipment screen on the title menu; damage numbers are applied server-side at game start and persist across the run.

The Caverns campaign (50 waves)

Pick Crystalline Caverns from the LEVEL dropdown on the Campaign panel to start the right-panel TD track. Preview, path shape, and slot grid are distinct from Desolate Depths.

Structure:

• Waves 1–30: scaled difficulty curve with crystal-themed enemy mixes. Uses the same enemy pool as Desolate Depths plus miniboss variants.
• Waves 31–39: hand-crafted pressure phase introducing dense prism packs, splitter flocks, and stealth phantoms that punish under-specced detection.
• Wave 35 miniboss: Crystal Titan — 450 HP, heavy armor, projects a shield aura to nearby allies.
• Waves 40–49: template-scaled waves driven by the shared wave generator. Deterministic seed keeps MP runs in sync.
• Wave 50 boss: Prism Warden — 1800 HP, reflects light damage, summons orb minions at 75 %, 50 %, and 25 % HP.

Victory at Wave 50 awards account-level rare drops (see Equipment).

Required build-out

The Caverns campaign is balanced around the three new T3 towers. You will struggle from wave 30 onward without at least one of them:

• Refraction Lens — chain splitter for crowds.
• Crystal Tuner — AoE damage + stun; the crystal eruption anchors your defense line.
• Prismatic Beam — heavy chain damage for tough mid-clusters.

All three recipes unlock via the arcane_towers tech node and require caverns resources.

Strategy tips

• Harvest a small stockpile of caverns resources before unlocking T3 towers — the recipes are expensive.
• Geode Crawlers block your path with armor. Use the first-hit malus to your advantage: focus-target a crawler with your strongest swing right after it aggros.
• The Prism Warden boss reflects light damage (crystal_beam, prismatic_beam). Bring a mix — don't wall-of-beam it.
• In co-op, drops on the Caverns floor are shared — anyone can pick up. Coordinate runs so the player short on prisms goes to the kills.