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.

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. Fully synced in multiplayer — every player sees the same order enforcement and healing penalty, not just the host.
• Mini Stats — Customize MiniBonemass HP, damage, speed, attack range, and damage resistances independently.
• Mini Leash — Minions that wander too far from the main body are teleported back near it, so they can't be kited away indefinitely (configurable distance).
• Always-Visible Nameplates — MiniBonemass names are always shown, not just when directly aimed at.
• Throw Summon — Throw attacks have a chance to spawn additional minions. The throw attack itself can now be blocked with a shield.
• Phase Messages — Custom HUD messages.

Moder

• Air Breath — Fires frost breath while airborne. Now deals damage continuously for the duration of the breath (tick rate, duration, damage, and knockback all configurable) instead of a single hit, and can be blocked or dodged throughout.
• Ground Breath — The dragon's grounded breath attack now works the same way — continuous multi-hit damage for as long as the breath lasts, blockable/dodgeable the entire time (previously only a single hit registered no matter how long the breath animation played).
• Dragon Strike — When landing, Moder aims at a player and slams down on that exact spot after a configurable delay (giving you time to move away). The impact deals blunt damage and knockback through the normal hit pipeline — block or dodge it like any other attack.
• Dragon Fear — AOE roar triggered below HP threshold. Deals frost damage and, if you fail to dodge-roll out of it, inflicts a short "Stunned" status effect that disables movement, blocking, and dodging entirely — a shield won't stop the fear itself (only a well-timed roll will), though it still reduces the roar's direct damage.

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.

Changelog

⚠️ Known Issues (v1.1.1)

• Bonemass Mini Split currently requires the MonsterDB mod. BossAdd's own built-in registration for the Mini Bonemass prefabs is temporarily disabled to avoid conflicting with MonsterDB's prefab setup. Until MonsterDB is updated for Valheim 1.0, Mini Bonemass may not spawn at all, and related features (kill-order enforcement, nameplates) may not work correctly without it installed. This will be revisited once MonsterDB is updated.
• Moder's "Dragon Fear" stun effect is not currently working. The status effect itself fails to apply, so the roar currently only deals damage. This ability is planned to be replaced with a different mechanic soon, so it will not receive a separate fix in the meantime.

v1.1.1

• Valheim 1.0 — Re-validated the entire mod against the official Valheim 1.0 release and confirmed compatibility.
• Eikthyr — Lightning Strike can now be blocked with a shield.
• Eikthyr — The burning effect from Lightning Strike now goes out normally when you get wet or stand in the rain, instead of never extinguishing.
• The Elder — Boulder Throw now knocks players back on impact.
• Bonemass — The ooze throw attack can now be blocked with a shield, and hit accuracy has been significantly improved.
• Bonemass — Blocking the ooze throw still applies the "Filthy" slow effect even on a clean full block — only the damage is reduced, the slow always goes through.
• Bonemass — Fixed Mini Bonemass kill-order enforcement not actually working — attacking them out of the required color order no longer results in an unintended kill.
• Bonemass — Mini Bonemass nameplates now display correctly for every player, not just the host.
• Bonemass — Minions that wander too far from the main body are teleported back near it, so they can't be kited away indefinitely.
• Moder — Removed the Frost Clone and Ice Field mechanics entirely.
• Moder — Ground Breath and Air Breath now deal damage continuously for as long as the breath lasts, instead of registering only a single hit no matter how long the animation played. Blockable and dodgeable throughout, and now cause a stagger reaction on hit.
• Moder — The landing roar has been reworked into "Dragon Fear" — failing to dodge it inflicts a brief Stunned status effect. (Currently not working — see Known Issues above. Slated for replacement with a different ability soon.)
• Moder — New attack on landing: "Dragon Strike" — an expanding shockwave ring spreads out from the landing spot and follows the terrain's shape naturally. Blockable (still knocks you back even when blocked) and fully avoidable with a well-timed dodge-roll. A stomp impact effect plays the instant Moder touches down.

v1.1.0

• Moder — Ground Breath and Air Breath now deal damage continuously while the breath is active, instead of registering only a single hit no matter how long the breath animation played. You can block them with a shield or dodge-roll through them at any point during the breath.
• Eikthyr — Lightning Strike can now be blocked with a shield and properly knocks you back (the knockback was silently broken before and never actually pushed anyone).
• Eikthyr — The burning effect from Lightning Strike now goes out normally when you get wet or stand in the rain, instead of never extinguishing.
• The Elder — Boulder Throw impacts (both the direct hit and the splash) now properly knock players back.
• Bonemass — The ooze throw attack can now be blocked with a shield.
• Bonemass — Fixed a rare case where a single massive hit could kill Bonemass outright and skip the minion-split phase entirely, making the fight impossible to finish normally.
• Bonemass — Mini Bonemass kill-order enforcement (and the healing penalty for breaking it) now works correctly and consistently for every player in multiplayer, not just the host.
• Bonemass — Fixed non-host players occasionally getting kill credit/experience for Bonemass without the fight actually being finished.
• Bonemass — Mini Bonemass nameplates are now always visible instead of only flashing briefly when directly aimed at.
• Bonemass — Minions that wander too far from the main body are now teleported back near it, so they can no longer be kited away indefinitely.
• Bonemass — Fixed a bug where reloading mid-fight (e.g. after a disconnect or crash) could leave Bonemass permanently unkillable; it now automatically detects and recovers from this on its own.
• Stability — Boss mechanics are now isolated from each other, so a problem in one no longer silently prevents other mechanics (or even basic respawn checks) from running that frame.

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.

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)