diff --git a/src/bosses.lua b/src/bosses.lua
new file mode 100644
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+++ b/src/bosses.lua
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+-- Named floor bosses: rare, sturdier variants of the bestiary that phase-shift
+-- once bloodied ("enrage") and always drop a superior, boss-exclusive
+-- artifact on death. A boss is otherwise a plain monster entity - it rides
+-- the same scheduler, ai.lua behaviour and abilities.lua dispatch as every
+-- other creature - so this module only adds what is genuinely new: the
+-- catalog, the enrage phase check, and the guaranteed drop.
+--
+-- A boss's second, harder-won phase - the brace-then-unleash cataclysm once
+-- it is battered all the way down to desperateAt - lives in phases.lua
+-- instead of here, since unlike enrage it spends whole turns and needs its
+-- own two-state machine; this module only supplies the catalog numbers
+-- (desperateAt, desperateDefenseBonus, novaDamage, novaRadius) it reads.
+--
+-- Builder places at most one per floor from depth 6 on, its rarity roll
+-- appended after every other placement (artifacts included) so it can never
+-- perturb an earlier system's rng sequence, exactly like artifacts.lua does
+-- for its own roll. Gating at depth 6+ also keeps bosses off every floor the
+-- fixed-maxDepth win-condition tests generate (those use maxDepth <= 3).
+
+local Entity = require("entity")
+local Artifacts = require("artifacts")
+
+local Bosses = {}
+
+Bosses.catalog = {
+  {
+    key = "warlord", glyph = "W", name = "the Orc Warlord",
+    hp = 34, attack = 7, defense = 3, speed = 100, ai = "pack",
+    minDepth = 6, xp = 40, ability = "rally",
+    enrageAt = 0.5, enrageAttack = 4, enrageSpeed = 25, enrageHeal = 6,
+    desperateAt = 0.2, desperateDefenseBonus = 5, novaDamage = 12, novaRadius = 2,
+    lootKey = "warlords_cleaver",
+  },
+  {
+    key = "lich", glyph = "L", name = "the Lich",
+    hp = 28, attack = 5, defense = 2, speed = 100, ai = "flee", range = 6,
+    minDepth = 7, xp = 45, ability = "curse",
+    enrageAt = 0.5, enrageAttack = 3, enrageSpeed = 20, enrageHeal = 8,
+    desperateAt = 0.2, desperateDefenseBonus = 4, novaDamage = 10, novaRadius = 2,
+    lootKey = "lich_phylactery",
+  },
+  {
+    key = "bonequeen", glyph = "Q", name = "the Bone Queen",
+    hp = 32, attack = 4, defense = 2, speed = 95, ai = "flee",
+    minDepth = 8, xp = 50, ability = "summon", summonSpecies = "zombie",
+    enrageAt = 0.5, enrageAttack = 3, enrageSpeed = 15, enrageHeal = 10,
+    desperateAt = 0.2, desperateDefenseBonus = 4, novaDamage = 11, novaRadius = 2,
+    lootKey = "bone_queen_carapace",
+  },
+}
+
+Bosses.byKey = {}
+for _, spec in ipairs(Bosses.catalog) do
+  Bosses.byKey[spec.key] = spec
+end
+
+-- Boss species eligible at a depth, in registry order, mirroring
+-- Monsters.forDepth so builder.lua can roll among them the same way.
+function Bosses.forDepth(depth)
+  local eligible = {}
+  for _, spec in ipairs(Bosses.catalog) do
+    if spec.minDepth <= depth then eligible[#eligible + 1] = spec end
+  end
+  return eligible
+end
+
+function Bosses.create(spec, id, x, y)
+  local entity = Entity.new({
+    id = id, x = x, y = y,
+    glyph = spec.glyph, name = spec.name, kind = "monster",
+    species = "boss_" .. spec.key, ai = spec.ai,
+    hp = spec.hp, maxHp = spec.hp,
+    attack = spec.attack, defense = spec.defense,
+    speed = spec.speed, range = spec.range or 0,
+  })
+  entity.ability = spec.ability
+  entity.summonSpecies = spec.summonSpecies
+  entity.cooldown = 0
+  entity.isBoss = true
+  entity.bossKey = spec.key
+  entity.enraged = false
+  -- Always alert: sneaking up on a named boss is not part of the design
+  -- (see stealth.lua's header for how this differs from a wild monster).
+  entity.awareness = "hunting"
+  return entity
+end
+
+-- Xp reward for felling a boss, looked up by the bossKey stamped onto it at
+-- creation. Falls back to a flat amount for a boss entity missing one, which
+-- should not happen outside of a malformed save.
+function Bosses.xpFor(entity)
+  local spec = Bosses.byKey[entity.bossKey]
+  return spec and spec.xp or 20
+end
+
+-- Checked at the start of a boss's own turn, after status ticks, hazards and
+-- regen but before its ability or plain ai runs: once bloodied past its
+-- enrageAt threshold it permanently gains attack and speed and takes a
+-- one-time heal, exactly once for the rest of the fight. Mirrors the direct
+-- stat-field mutation classes.lua uses for a permanent delta, rather than a
+-- status.lua effect, since this should never expire or be cleansed.
+function Bosses.tryEnrage(monster)
+  if not monster.isBoss or monster.enraged or not monster:isAlive() then return nil end
+  local spec = Bosses.byKey[monster.bossKey]
+  if not spec then return nil end
+  if monster.hp > monster.maxHp * spec.enrageAt then return nil end
+  monster.enraged = true
+  monster.attack = monster.attack + spec.enrageAttack
+  monster.baseAttack = monster.baseAttack + spec.enrageAttack
+  monster.speed = monster.speed + spec.enrageSpeed
+  monster.hp = math.min(monster.maxHp, monster.hp + spec.enrageHeal)
+  return string.format("%s flies into a bloodied rage", monster.name)
+end
+
+-- The guaranteed superior artifact a boss drops on death, dropped straight
+-- onto the floor at its corpse's feet by Game:awardKill rather than rolled
+-- into the ordinary loot table builder.lua scatters at level generation.
+function Bosses.lootFor(entity)
+  local spec = Bosses.byKey[entity.bossKey]
+  if not spec then return nil end
+  return Artifacts.create(spec.lootKey)
+end
+
+return Bosses