ProgressiveSerpentSpawner

Progressive Serpent Spawner

English | Português

English

Sea Serpents are one of the rarest encounters in Valheim. In vanilla they have only a 5% chance to spawn, and that roll happens roughly once every 1000 seconds per ocean zone. Many players finish the game without ever seeing one.

Progressive Serpent Spawner makes the ocean far more dangerous as your world progresses. Every boss defeated raises the serpent spawn chance, and by default it reaches 100% after the 4th boss. Want them rarer? Every value is configurable.

How it works

• The mod reads the vanilla serpent spawn chance directly from the game. It doesn't hardcode values, so it keeps working if the game changes them.
• All vanilla spawn conditions stay exactly the same: ocean biome, night or rain/thunderstorm, spawn interval, and max of 1 serpent.
• Progression is counted with the world's global keys (defeated_eikthyr, defeated_gdking, etc.). These are synced by the server, so everyone shares the same progression.
• The chance is recalculated automatically a few seconds after a boss dies. No restart needed.

Formula:

final chance = base × (1 + BonusPerBoss × bosses defeated)

The result is clamped between the vanilla base and MaxChance.

Default progression

| Bosses defeated | 0 | 1 | 2 | 3 | 4+ |

|---|---|---|---|---|---|

| Spawn chance | 5% | 30% | 55% | 80% | 100% |

Even at 100%, vanilla limits still apply: one roll every ~1000s per ocean zone, only at night or during rain/thunderstorm, and max 1 serpent at a time.

Configuration

The config file is created at BepInEx/config/ProgressiveSerpentSpawner.cfg after the first launch.

| Setting | Default | Description |

|---|---|---|

| Enabled | true | Turns the spawn adjustment on or off. |

| TargetPrefabs | Serpent | Comma-separated list of creature prefabs affected by the mod. |

| BossKeys | all 7 vanilla bosses | Global keys that count as progression. Each key present adds +1 boss. |

| BonusPerBoss | 5 | Multiplier added per boss defeated (0 to 5). 5 with 1 boss = base × 6. |

| MaxChance | 100 | Hard cap for the spawn chance (0 to 100%). |

| BaseChanceOverride | -1 | If >= 0, ignores the vanilla chance and uses this value (%) as base. -1 = use vanilla. |

| VerboseLog | true | Logs the serpent spawn data and every recalculation. |

Tuning tips (for rarer serpents)

• Rare: BonusPerBoss = 0.35, MaxChance = 20 (ends at ~17% with 7 bosses)
• Very rare: BonusPerBoss = 0.25, MaxChance = 15 (ends at ~13.75%)

Multiplayer

• Install the mod on the server and all clients.
• In Valheim, spawns are handled by whoever owns the zone, which is usually a player. Keep the same config on everyone so spawn rates are consistent.
• Boss progression comes from the server's global keys, so it's always shared.

Testing

With devcommands enabled:

listkeys

setkey defeated_eikthyr

removekey defeated_eikthyr

Check BepInEx/LogOutput.log for the [Registro] and [Recalc] lines to see the current spawn chance.

Compatibility

• Works with vanilla spawn data.
• Mods that fully replace world spawn tables (e.g. Spawn That, Expand World Spawns) may override or conflict with the serpent spawn entries. If you use one of them, configure serpent spawns there instead.

Support

Found a bug or have a suggestion? Reach me on Discord: Padilha

If you enjoy the mod and want to support development:

Donate via PayPal

Português

As Serpentes Marinhas são um dos encontros mais raros do Valheim. No vanilla elas têm só 5% de chance de spawnar, e essa rolagem acontece mais ou menos uma vez a cada 1000 segundos por zona de oceano. Muita gente termina o jogo sem nunca ver uma.

O Progressive Serpent Spawner deixa o oceano bem mais perigoso conforme o mundo progride. Cada boss derrotado aumenta a chance de spawn da serpente e, por padrão, ela chega a 100% depois do 4º boss. Quer elas mais raras? Todos os valores são configuráveis.

Como funciona

• O mod lê a chance de spawn vanilla da serpente direto do jogo. Nada é fixo no código, então continua funcionando se o jogo