BossAdd

BossAdd adds new mechanics and phase patterns to all 7 Valheim bosses.
Every feature is fully configurable via BepInEx ConfigurationManager (F1 key).
Supports English and Korean — auto-detected from your Valheim language setting.

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Features

Eikthyr

• Summon — Calls minions on HP thresholds, timer intervals, or both. Includes a special elite summon at low HP.
• Stomp Lightning — Stomp attacks trigger lightning strikes with a configurable burning DoT on hit and a safe zone radius.
• Horn Attack — Horn charge launches players with force matching the boss's actual melee attack range. Blocked while the player is dodge-invincible.
• Phase Messages — Custom HUD messages at configurable HP thresholds.

The Elder

• Tree Spawn — Grows trees around players when below HP threshold.
• Rock Throw Combo — The root-shoot attack triggers a configurable burst of boulder throws (count and interval), each with splash damage on impact.
• Phase Messages — Custom HUD messages.

Bonemass

• Split Summon — Splits into 5 MiniBonemass variants at HP threshold.
• Kill Condition — Bonemass cannot die until all MiniBonemass are defeated. Wrong kill order heals Bonemass.
• Mini Stats — Customize MiniBonemass HP, damage, speed, attack range, and damage resistances independently.
• Throw Summon — Throw attacks have a chance to spawn additional minions.
• Phase Messages — Custom HUD messages.

Moder

• Frost Clones — Splits into MiniModer clones at HP threshold.
• Mini Stats — Customize MiniModer scale, HP, damage, speed, and flight behavior.
• Air Breath — Fires frost breath while airborne.
• Landing Blast — Knocks back nearby players on landing.
• Freeze Roar — AOE frost attack triggered below HP threshold.
• Ice Field — Creates a persistent frost damage zone.

Yagluth

• Skeleton Summon — Summons Skeleton Warriors at 3 HP thresholds. While any Skeleton lives, Yagluth takes no damage.
• Death Zone — Forces a nova slam at HP threshold. Drains % max HP from all nearby players. VFX and radius configurable.
• Meteor Fire Patch — Meteor impacts leave lasting fire fields.
• Rage Mode — Accumulated damage triggers a berserk state with speed and damage bonuses.

The Queen

• HP Summon — Spawns brood at configurable HP intervals.
• Timer Summon — Spawns brood on a repeating timer during combat.
• Breath Summon — Breath attacks trigger additional minion spawns.
• Poison Field — Creates persistent poison damage zones along her movement path.

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Changelog

v1.0.5

• Bonemass — MiniBonemass now only uses melee attacks. Poison gas and the throw attack are no longer given to it, which also improves performance (fewer active status effects/projectiles).
• Bonemass — MiniBonemass now gets its own dedicated weapon data instead of sharing Bonemass's, so the attack range and attack interval multipliers actually take effect (previously had no real effect on behavior).
• Bonemass — New gimmick: while any MiniBonemass is still alive, the main Bonemass takes no damage (configurable on/off). Hit effects and sounds still play so it's clear the hit didn't count.
• Bonemass — Throw attack overhaul: the ooze blob now uses an exact parabolic trajectory that reliably lands on the targeted player, with configurable projectile speed, blunt/poison damage, and hit-detection radius.
• Bonemass — New status effect ("Filthy"): a successful throw hit now applies a movement-slow debuff, with configurable duration.
• Bonemass — Throw Summon (bonus monster spawn on throw) now spawns at the projectile's actual impact point instead of around the player, so it lines up with where the ooze actually landed.
• Multiplayer — Fixed MiniBonemass (split clones) and MiniModer (frost clones) not appearing at all for non-host players.
• Multiplayer — Guests can now see and fight clones normally instead of them silently failing to sync.
• BossStat — Fixed HP multiplier stacking across sessions/zone reloads for a persisted boss, which could make bosses effectively unkillable over time. It's now always recalculated from a cached original prefab value instead of the current (already-modified, possibly-saved) one.
• BossStat — Fixed the HP multiplier not applying to bosses summoned via the boss altar (it worked when spawned via console command, but not through normal altar summoning).
• BossStat — Fixed the attack speed multiplier not actually changing how often a boss attacks — it now correctly affects the weapon's real attack cooldown, not just an unused internal floor value.
• Eikthyr — Fixed the lightning attack's burning DoT applying even when the lightning strike itself was dodged. It now only applies on an actual hit.
• Stability — Fixed an issue that could cause infinite loading in certain situations, caused by a stale object reference left behind during VFX cleanup.
• Stability — Fixed several runtime exceptions that could stall combat hit detection or prevent monsters from equipping their weapon correctly.

v1.0.4

• Eikthyr — Removed the Fire Patch mechanic entirely.
• Eikthyr — Horn Attack launch range now matches the boss's actual melee attack range instead of a separate config value.
• Eikthyr — Horn Attack no longer launches players while they are dodge-invincible.
• Eikthyr — Removed the lightning telegraph (warning) delay and the lightning slow (shock) effect. The lightning burn DoT is unchanged.
• Eikthyr — Fixed a crash in Horn Attack caused by accessing a private ZNet field directly.
• All Bosses — Fixed a serious bug where HP, movement speed, and attack speed multipliers kept stacking every time a boss's zone reloaded (e.g. after a player died or reconnected mid-fight), eventually making bosses effectively unkillable or hyper-aggressive. Multipliers are now always calculated from a cached original value instead of the current (already-modified) one. Affects all 7 bosses.
• The Elder — Rock Throw is no longer an independent cooldown/chance-based ability. It now triggers as a configurable burst combo (count + interval) whenever the root-shoot attack fires.

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Requirements

• BepInEx for Valheim

Compatibility

BossAdd works with vanilla Valheim + BepInEx only — no monster database mods required.
All boss modifications (size, HP, damage, resistances) are handled internally via config values.

Note: Using BossAdd together with monster stat mods such as CLLC (CreatureLevelAndLootControl) may cause stat conflicts on mini-bosses (MiniBonemass, MiniModer). This is not officially supported.

Installation

Install via r2modman or Thunderstore Mod Manager (recommended).
Manual install: extract to BepInEx/plugins/bossadd/.

Configuration

Open the F1 menu in-game to adjust all settings per boss.
All features can be individually enabled or disabled.
Config file: BepInEx/config/bossadd.cfg

Language Support

The F1 menu descriptions automatically display in English or Korean
based on your Valheim language setting (Main Menu → Settings → Language).

Bug Reports & Support

Found a bug? Please report it so it can be fixed!

Join the Discord server via the Support section on the CaptainSkillTree mod page.
Post your report in the appropriate channel — responses are active.

When reporting, please include:

• What happened and what you expected
• Your mod list (other mods installed)
• The BepInEx log file (BepInEx/LogOutput.log)