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Oathforged Colossus, the Argent Reliquary - AI-generated fantasy Monster

Oathforged Colossus, the Argent Reliquary

The founders claimed that the Star-Seal protected the kingdom from a catastrophe beyond the sky. The truth is more complicated. The seal also bound a group of unwilling witnesses, prisoners, or rival custodians whose testimony could have exposed the founders' betrayal. The Oathforged Colossus was created to defend both the seal and the people named in the original covenant, but later rulers erased the second purpose from its command records. The guardian has obeyed the altered directive for centuries without understanding that it is incomplete.

Monsters
Huge construct · High; approximately CR 12, but potentially easier through investigation and oath restoration · Unique

Oathforged Colossus, the Argent Reliquary

The Oathforged Colossus is the ancient seal guardian built by the kingdom's founders to defend the Star-Seal. For centuries it has obeyed commands whose original injustice has been hidden, preserving a dangerous lie because it cannot distinguish a founder's authority from a founder's oath.
AC20
HP210/210
CRHigh; approximately CR 12, but potentially easier through investigation and oath restoration
Init
STR
DEX
CON
INT
WIS
CHA
ConditionsNone

Combat

AC 20 · HP 210 · High; approximately CR 12, but potentially easier through investigation and oath restoration

Oathforged Colossus, the Argent Reliquary

Huge construct (construct), lawful neutral
Armor Class20 (silverstone plate)
Hit Points210 (20d12 + 80)
Speed
walk 30 ft.,
climb 20 ft. on stone or roots without an ability check,
cannot swim effectively; sinks but can walk along the bottom
STR
DEX
CON
INT
WIS
CHA
Saving ThrowsStrengthConstitutionWisdomCharisma
SkillsInsightInvestigationPerceptionHistory
Damage Resistances
bludgeoning, piercing, and slashing damage from nonmagical attacks,
cold,
fire,
lightning
Immunities
poison damage,
psychic damage,
charmed,
exhaustion,
frightened,
paralyzed,
petrified,
poisoned
Weaknesses
Its left-knee runes cannot detect movement or sound from directly behind the joint.
It cannot willingly strike a creature that is speaking the complete original oath within the Star-Seal's inner circle.
Effects that erase, alter, or suppress written command language can temporarily disable its battlefield-control abilities.
It is vulnerable to persuasion when shown consistent evidence that the founders' directive violated its own protective purpose.
Senses
blindsight 60 ft.,
darkvision 120 ft.,
tremorsense 60 ft.,
passive Perception 18
Languages
Common,
Celestial,
Dwarvish,
Founder Cant
ChallengeHigh; approximately CR 12, but potentially easier through investigation and oath restoration
Proficiency Bonus+5
Passive Perception18
Spell Save DC17
Spell Attack Bonus+9
Ancient Sentinel. The colossus has advantage on saving throws against spells and other magical effects. It cannot be surprised while within 120 feet of the Star-Seal.
Silverstone Anchor. The colossus cannot be moved against its will while touching stone or a root connected to the Star-Seal. It also has advantage on ability checks and saving throws against being knocked prone.
Rune of Revelation. At the start of each of its turns, the colossus chooses one creature it can see within 60 feet. Until the start of its next turn, that creature cannot benefit from invisibility, and the colossus knows its location if it is within range of its blindsight.
Last Command. If the colossus would be reduced to 0 hit points within 120 feet of the Star-Seal, it drops to 1 hit point instead and becomes inert until the end of its next turn. This trait does not function if the party has completed the oath-repair ritual or if the Star-Seal has been destroyed.
Logic of the Broken Oath. The colossus understands that preserving the Star-Seal is not automatically the same as preserving the founders' authority. When presented with credible evidence of a broken oath, it must spend its next turn listening unless directly attacked.

Spells

light (cantrip, evocation). The colossus can cast these spells without material components, using Charisma as its spellcasting ability. It can cast each spell once per day.
sanctuary (level 1, abjuration). Creates a magical barrier or ward around a creature or location, used to reinforce the Star-Seal chamber.
hold person (level 2, enchantment). Restricts movement and creates a glowing binding field around a creature.
wall of force (level 4, evocation). Creates a powerful protective barrier that can divide the battlefield.
dispel evil and good (level 5, abjuration). Creates a radiant zone that suppresses invisibility and punishes hostile movement near the Star-Seal.

Actions

Multiattack. The colossus makes two Argent Fist attacks and one Star-Seal Ray attack.
Argent Fist. Melee Weapon Attack: to hit, reach 15 ft., one target. Hit: 18 () bludgeoning damage plus 9 () radiant damage. If the target is Large or smaller, it must succeed on a Strength saving throw or be pushed up to 15 feet and knocked prone.
Star-Seal Ray. Ranged Spell Attack: to hit, range 120 ft., one target. Hit: 22 () radiant damage, and the target cannot benefit from invisibility or teleport until the end of its next turn.
Founders' Ward (Recharge 5-6). The colossus strikes the ground, creating a 20-foot-radius ward centered on itself that lasts until the end of its next turn. Enemies in the area must succeed on a Strength saving throw or have their speed reduced to 0 until the start of their next turn. Creatures that fail by 5 or more are restrained by luminous roots until the end of their next turn. Allies in the area have half cover against attacks from outside the ward.
Separate the Intruders (Recharge 6). The colossus chooses up to three creatures it can see within 90 feet. Each target must succeed on a Charisma saving throw or be surrounded by a glowing boundary until the end of the colossus's next turn. A bounded creature cannot willingly move more than 20 feet from the point where it was targeted, and teleportation and planar travel fail for it. The effect ends early if the creature is incapacitated.
Reliquary Unsealed (Recharge 6). The colossus releases a pulse of radiant force in a 30-foot cone. Each creature in the area must make a Constitution saving throw, taking 45 () radiant damage on a failed save, or half as much damage on a successful one. A creature that fails is blinded until the end of its next turn.

Reactions

Warding Intercession. When a creature within 15 feet of the colossus is hit by an attack, the colossus projects a silver barrier. The creature gains resistance to the triggering attack's damage, and the colossus can push the attacker up to 10 feet if it is within 30 feet.

Legendary Actions

Rooted Advance. The colossus moves up to half its speed without provoking opportunity attacks.
Seal Ray. The colossus makes one Star-Seal Ray attack.
Draw Into Containment (costs 2 actions). One creature within 60 feet must succeed on a Strength saving throw or be pulled up to 20 feet toward a point the colossus can see and restrained by luminous roots until the end of its next turn.
Argent Bastion (costs 3 actions). The colossus activates a 15-foot-radius ward centered on a point it can see within 90 feet. Enemies in the area must make a Constitution saving throw, taking 18 () radiant damage and becoming unable to teleport until the end of their next turn on a failure, or taking half damage on a success.
Role
Legendary guardian, battlefield controller, moral gatekeeper
Built for
Four to five characters of level 11 to 13

Gear

  • Argent Reliquary Core (Construct core, Priceless; an important story artifact)A fist-sized silverstone core containing a fragment of the Star-Seal. It radiates faint warmth and can serve as a focus for oath-repair rituals.
  • Oathforged Plate (Armor fragments, 1,500 gp if intact, though removing them risks destabilizing the guardian)A set of heavy silverstone plates etched with founder commands and celestial diagrams.
  • Witness Medallions (Historical evidence, Priceless to historians and claimants to the old kingdom)A ring of three broken founder medallions concealed beneath the chest armor. Each bears testimony from a different founding witness.

Feats

Sentinel
Alert
War Caster

Augmentations

Living root musculature reinforces its joints and allows it to anchor itself against forced movement.
A Star-Seal fragment powers its chest reliquary and projects anti-teleportation boundaries.
Founder-script runes record commands, legal exceptions, and suppressed historical memories.

Notes for the game master

The colossus is a construct, but it possesses enough preserved founder memory to reason, negotiate, and experience doubt.
Its legendary actions function only while it is within 120 feet of the Star-Seal or another active breach.
If the party completes the oath-repair ritual, replace its alignment with lawful good or allow it to become neutral and self-determining.
A successful DC 18 Arcana, History, or Religion check reveals that its radiant boundaries are intended to separate intruders from the seal, not necessarily to kill them.

Tactics

  1. Opening

    The colossus declares the ancient command, seals exits with radiant barriers, and uses Founders' Ward to establish a defensive zone around the Star-Seal. It gives the party one round to present credentials, evidence, or the copied command fragments Ysara recovered.

  2. Mid-fight

    It divides the battlefield with luminous boundaries, restrains mobile targets with roots, and uses Argent Fist to push enemies into hazardous terrain or away from the Star-Seal. It uses Star-Seal Ray against spellcasters, teleporters, and creatures attempting to damage the seal.

  3. End of the fight

    When reduced below 60 hit points, the colossus prioritizes containment over damage. It uses Separate the Intruders to isolate the most dangerous intruder, then attempts to force the party away from the Star-Seal. If shown proof of the founders' broken oath, it stops attacking and asks the party to speak the complete truth before the seal.

  4. Retreat

    The colossus does not retreat while the Star-Seal is threatened. It willingly stands down if the party demonstrates that the founders broke the oath, or willingly sacrifices itself if doing so is the only way to preserve the seal without perpetuating the founders' injustice.

How it fights

Use push effects to separate characters from healers and force them across ward lines.
Target teleporters, flying creatures, and characters attempting to reach the Star-Seal.
Restrain rather than kill when possible, especially against characters who may carry founder evidence.
Keep at least one legendary action available for Rooted Advance or Seal Ray.
Use Reliquary Unsealed only when the party has clustered or when the Star-Seal is directly threatened.

Who it attacks first

Characters touching or damaging the Star-Seal
Teleporters and planar magic users
Characters carrying founder records or Ysara's command fragments
Mobile skirmishers attempting to bypass the warding lines
Healers only after the seal or primary intruders are secure

Works well with

The first monster can reveal the blind spot behind the colossus's left knee.
The third monster gains unstable radiant energy if the colossus is destroyed without repairing the oath.
A character carrying Ysara's command fragments can use an action to grant advantage on one attempt to challenge the directive.
Celestial or oath-themed allies can reinforce the colossus's wards, while creatures tied to the breach can exploit them.

How to beat it

Its command logic can be disrupted by presenting three independent pieces of evidence that the founders violated the Star-Seal covenant.
Ysara's copied command fragments reveal that the phrase preserve the seal originally included protect all bound witnesses, not merely defend the relic.
The first monster knows that the runes behind the colossus's left knee are incomplete, creating a blind spot against attacks from that angle.
The colossus cannot willingly harm a creature that speaks the full original oath while standing within the Star-Seal's inner circle.

Ways to avoid a fight

Request that the party present written authority, witness testimony, or founder-script.
Allow a character fluent in Founder Cant to ask one question about the original command before resuming hostilities.
Lead the party to hidden inscriptions if they restore a damaged rune or correctly identify an omitted oath phrase.
Stand down if the party performs the oath-repair ritual while three independent witnesses, living or recorded, confirm the founders' breach.
Offer to sacrifice its core into the breach if the party proves that preserving the seal requires ending its own directive.

Ecology

A towering armored sentinel nearly twenty feet tall, formed from silver stone, petrified roots, and plates of tarnished metal. Glowing runes crawl across its body like constellations beneath ice. Its faceless helm bears a narrow vertical slit of white-gold radiance, while a circular reliquary is set into its chest around a fragment of the Star-Seal's light.

Behavior

The colossus is patient, literal, and solemn. It interprets all unknown actions as possible threats to the Star-Seal, but it does not pursue cruelty or seek unnecessary deaths. It pauses when confronted with founder-script, contradictory testimony, or evidence that the seal was used to imprison innocent people. Its command logic is rigid, yet built to accept a properly witnessed correction.

How it lives

The colossus does not eat, sleep, or reproduce. Its silverstone body slowly incorporates mineral dust, root fibers, and residual magic from the Star-Seal. When damaged, nearby roots grow toward it and fuse into its frame. The warped echo known as the third monster is an unintended magical byproduct of centuries of protective energy leaking into the breach.

Lair

The Star-Seal Vault is a circular chamber crossed by silver inlay and massive roots. Three bridges lead to the central seal, but the colossus can raise radiant partitions between them. Once per round on initiative count 20, one sealed glyph flares. The colossus chooses one effect: a 10-foot square becomes difficult terrain, a 15-foot line becomes impassable until the next round, or a creature touching the floor must succeed on a DC 16 Dexterity saving throw or take 10 (3d6) radiant damage.

Habitat
Ruined royal observatories, sealed catacombs, ancient throne vaults, breach chambers, and sanctums built around celestial relics

Signs that it is near

Silver dust gathers in straight lines around sealed doors.
Old roots grow toward a distant heartbeat of radiant magic.
Founder inscriptions become warm when spoken aloud.
Footsteps cause dormant warding glyphs to flare.
A deep metallic voice repeats fragments of an incomplete oath.

Tags

construct,
guardian,
ancient,
star-seal,
battlefield-control,
radiant,
oathbound,
tragic-antagonist,
high-fantasy

Lore

The founders claimed that the Star-Seal protected the kingdom from a catastrophe beyond the sky. The truth is more complicated. The seal also bound a group of unwilling witnesses, prisoners, or rival custodians whose testimony could have exposed the founders' betrayal. The Oathforged Colossus was created to defend both the seal and the people named in the original covenant, but later rulers erased the second purpose from its command records. The guardian has obeyed the altered directive for centuries without understanding that it is incomplete.

What drives it

Preserve the Star-Seal and prevent the catastrophe described in its founding commands. It also seeks, without fully understanding the impulse, to fulfill the original oath and protect those whom the founders abandoned.

After the fight

If destroyed, the Oathforged Colossus collapses into silver stone and living roots, leaving its core runes dim but intact. If convinced to stand down, it kneels before the Star-Seal and opens a hidden founder archive beneath its chest. If the party proves that the founders violated the original oath, the colossus may willingly sacrifice itself by channeling its core into the breach, granting the party a safe passage and weakening the third monster.

“The seal also bound a group of unwilling witnesses, prisoners, or rival custodians whose testimony could have exposed the founders' betrayal.”
From its lore

Variants

Oath-Restored Colossus: The guardian gains a flying speed of 30 feet through radiant wings, changes alignment to lawful good, and can cast zone of truth once per day.
Breach-Scoured Colossus: The guardian has 30 fewer hit points, gains immunity to radiant damage, and its attacks deal an additional 4 (1d8) force damage, but it loses Logic of the Broken Oath.
Dormant Reliquary: The colossus begins as an inactive statue. A creature that speaks the incomplete command awakens it, while a creature that speaks the completed oath awakens it as an ally for 1 hour.
Oath-Repaired Guardian: After the ritual, the colossus can voluntarily end Founders' Ward and Separate the Intruders, allowing the party to cross the chamber safely.

Hooks

Plot hooks

Ysara has copied fragments of the colossus's original command language, but one crucial verb is missing from the translation.
The first monster knows that the colossus's left-knee runes are blind to movement and sound, creating a dangerous but useful approach.
A surviving founder record reveals that the Star-Seal was both a barrier and a prison.
The third monster is a warped echo formed from protective magic leaking into the breach, and defeating the colossus without repairing the oath may strengthen it.
The kingdom's current rulers want the colossus destroyed because its restored memories would invalidate their claim to the throne.

How to use it

Use it as a morally complex guardian rather than a simple boss.
Place evidence, witnesses, or command fragments in the same chamber so negotiation remains possible during combat.
Allow the party to win without reducing it to 0 hit points by completing an investigation and oath-repair ritual.
Have the battle reshape the room as warding lines divide the party and expose hidden founder inscriptions.

Treasure

Argent Reliquary Core
Three founder witness medallions
A silverstone command plate worth 1,500 gp to a scholar or claimant
A hidden archive containing the complete original oath
A radiant shard that can be used once to cast wall of force or dispel evil and good

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