‘Heart of the Iron God’ Part 2 – Adventure for 13th-Level Characters

This is the second part to my 5th edition conversion of the 3rd edition adventure, ‘Heart of the Iron God.’ It covers the first twelve chambers of the Colossus.

If you haven’t already viewed the first part already, be sure to start there.

‘Heart of the Iron God’ Index

Colossus Chambers

Note that all descriptions assume the Colossus is facing south.

1. Feet

This curved chamber of burnished iron is lit from sunlight streaming through an arch set into the Colossus’s foot. A heavy steel portcullis has been built into this arch, and a large wooden winch set into the wall nearby seems to lower and raise it. In the northern half of the chamber, a steel pillar rises into the ceiling a doorway set into the pillar allows you to notice a glowing disc of energy set into the floor of what appears to be an ascending chute. A smell steel lever is set beside the winch. A small gnome stands guard with his hands on the winch; he appears unarmed.

Each foot contains an identical chamber. The winch controls the portcullis, and the lever activates the disc (a permanent Tenser’s floating disc) that takes passengers up the leg of the Colossus. It takes 3 rounds to reach area 3. Each disc can carry a maximum of 500 pounds.


One gnome commoner. stands guard in each foot. If the PCs appear outside the portcullis, they shriek and flee from the room via the floating discs unless charmed or otherwise prevented from departing.

2. The Bog Room

This chamber is flanked by twin portals that access chambers within the Colossus. A more impressive pair of brass double doors are set into the south wall. A pair of large arrow slits in the north wall allow twin streams of sunlight to illuminate this chamber. A heavy circular trapdoor is set into a stone dais in the center of the floor.

Fifty pounds of downward pressure pushes the trapdoor open. This trapdoor is used both as a latrine and disposal area, giving this chamber the name of “the bog room.” Through the trapdoor is a 75-foot drop to the ground below. The ceiling above is an illusory ceiling leading to area 10.

3. Entry Chambers

Eerie magical light fills this plain metal room. A simple iron door allows access to and from the chamber. A massive cylindrical pillar crafted of tarnished steel goes from the floor to the ceiling, and a doorway allows entrance into the chute within. A lever is set within this strange pillar’ you also notice an identical lever in the corner of the chamber.

The lever against the wall raises and lowers the Tenser’s floating discs described in area 1 and the lever inside the shaft stops the disc. Each shaft heads up (to area 17) and down (to area 1).

4. Briefing Room

This plush chamber is well furnished with a massive table of polished dark wood surrounded by an array of finely crafted seats. Wide arrow slits adorn multiple walls, negating the need for magical light. A narrow staircase of greenstone allows access to the level above, and a pair of massive bronze doors leads to further rooms on this level. What appears to be a fireplace is set into the southwestern corner of the room, and hot air wafts up from the depths below. A large chart on the wall depicts the geography of a land unknown to you, with several large pins stuck into the map in a curved formation across the wall.

This chamber is used as a room by Xentarich to brief the crew before a major attack. The fireplace is actually the access hole to a small chute heated by a furnace below, accessible by a small steel ladder. The chute is thin and only a Small or smaller character could climb it with a successful DC 20 Strength (Athletics) check. Below this area is a hot furnace. Entering it is potentially deadly (8d6 points of fire damage per round). The chute heads up to similar heaters in areas 7, 15, and 19, and finally the chimney on the Colossus’s shoulder.


Boris and Riskat, two Nighthawks (see the appendix) wait here, armed with bows and peering out the arrow slits to the south. They attack if disturbed.

Tactics. The Nighthawks might hear the PCs approaching, in which case they hide and try to ambush the characters when they enter the room. The mercenaries fight with their bows as long as possible, focusing on the same target and trying to take on character down quickly. If one Nighthawk dies, the other tries to flee and sound the alarm.


A chart on the north wall shows a map of Xentarich’s homeland and a planned course for the Colossus. This chart could be very valuable to explorers and is worth 600 gp to the right buyer. The pins represent the route of the Colossus, back to the hidden base described in area 16.


The staircase leading up is trapped. When exposed to at least 100 pounds of pressure, the seventh step triggers a collapse of the stairs into a smooth ramp of stone that sends those ascending sliding back down into the room. At the same time, a secret trapdoor opens at the base of the steps. Unless those PCs on the stairs make a successful DC 15 Dexterity saving throw, they tumble backward through the hole and into the furnace below and take 28 (8d6) fire damage. A DC 13 Wisdom (Perception) check is required to see the ladder that allows an escape from the flames. The trap is noticeable with a successful DC 15 Intelligence (Investigation) check and can be disabled with a successful DC 18 Dexterity check using thieves’ tools.

5. Engineering

This cramped chamber is forged of black iron. The chamber is densely packed with heavy machinery and gears that grind and pound against each other, producing a thunderous rhythm of mechanical noise. Steam pours from cooling vents, and through the crowded chamber, you can see two heavy doors. You are deep within the Colossus, and this appears to be a vital section of the construction. Presently three gnomes wearing thick gloves and protective goggles jabber in a high pitched tone over a shattered pipe. A heavy red mist pours from the wrecked conduit, and a high pitched klaxon can be heard in the background. A heavy iron hatch is set in the floor of this dark chamber.

In addition to the two doors and the hatch, a secret door is hidden in the east wall. It can be found with a successful DC 19 Intelligence (Investigation) check. It is locked with a key carried by Xentarich; the lock can be picked with a successful DC 19 Dexterity check using thieves’ tools.

A character who examines the room and makes a successful DC 19 Intelligence (History) check could cause enough damage to create a selected effect from the power failure chart (see below). A failed or unskilled attempt at sabotage creates a random power failure. A hatch in the floor allows access to a cramped labyrinth of gears and pips under the floor that only a Small or smaller creature can fit into comfortably. If a power failure is triggered, this area must be entered and a successful DC 20 Intelligence (History) skill check must be made to restore power. In the event of a power failure, Glymm and Khrull head to this room to repair the damage.


If the PCs stop the three gnome commoners in their task, they shriek in Gnome that they must be allowed to fix the damage. If they do not resume their labor within 2 rounds, roll on the power failure chart below. This is a good opportunity for roleplaying (especially if they cannot understand the language and must communicate some other way). If the PCs aid the gnomes in their task the little engineers are extremely friendly and helpful. The gnomes can be easily persuaded with a DC 15 Charisma (Intimidation or Persuasion) check to give vital details on the layout and area of the Colossus and only rush to sound the alarm immediately if they feel the Colossus is threatened. Unless convinced otherwise, they reveal the PCs’ location as soon as they encounter another one of Xentarich’s mercenaries. They come by on regular patrols every hour; assume the last patrol came by just before the PCs arrived unless you want to add some pressure by sounding an alarm within the next few minutes after the PCs leave the engineering bay. Persuading the gnomes not to reveal the characters’ presence requires a successful DC 19 Charisma (Intimidation or Persuasion) check. They might even reveal the password to gain access to area 25 if the PCs are exceptionally convincing, passing the check by 5 or more.

Power Failure

d100 Effect
1-23 Lower gear failure. The Colossus’s legs no longer move.
24-42 Field failure. The fields in area 18 fail, releasing the creatures within (see area 18 for details).
43-62 Power build up. Warning bells go off and smoke fills the room. After 5 minutes, the entire level is swept by a massive explosion. Each creature in the area must succeed on a DC 20 Dexterity saving throw, taking 10d6 fire damage on a failed saving throw, or half as much on a successful one. The Colossus is still intact but is immobilized and requires three days of 10,000 gp in materials to repair.
63-84 Upper gear failure. The Colossus’s arms no longer move.
85-94 Magical conduits failure. All magical effects (except the fields in area 18) fail. This includes all lighting, the levitation discs, and the construct’s eyes.
95-100 Complete power failure. All of the above effects (this does not destroy the spirit of the Colossus, however).

6. Food Storage

This chamber appears to be a storage area. Large creates filled with food are stacked against the walls, with large barrels of water nearby. The room holds enough supplies to last for many weeks. You can hear a low rumbling noise from the east wall. No other exits lead from this chamber.

The chamber holds little of interest, save extra provisions should the characters desire them.

7. Kitchens

You have entered the kitchen of this giant, mobile fortress. A pot of gruel slowly cooks over a fireplace. The room is currently deserted, and you spot an array of basic cooking implements lying on a table in the center of the room. The room smells of cooked meat and scented herbs. Two plain wooden doors lead from this room.

The fireplace is heated by the furnace below area 4. The cooks are long gone, eaten by the bugbears several weeks ago. The gnomes act as the new cooks, but they are presently performing required maintenance in area 5.

8. Storage

This narrow chamber is crammed with an array of boxes containing basic supplies and equipment. You spot piles of rope, poles, ladders, wheels, vials of oil, spare pipes, buckets, and large metal plates stacked in piles. The motion and noise from the engine room behind you make the room vibrate slightly. You spot another door partially hidden by wooden crates.

A successful DC 16 Intelligence (Investigation) check reveals a crumpled plan of the Colossus’s engines left forgotten in the corner under a coil of rope. If examined, this allows a character to make all Intelligence checks regarding the Colossus’ operation and engineering with advantage.


A vial has been placed precariously above the door to Khrull’s chamber (area 9). If the door is opened, the vial falls forwards and breaks apart. Every creature within 5 feet of the door must succeed on a DC 15 Dexterity saving throw or are covered in a stench so foul that anyone within 5 feet must make a DC 15 Constitution saving throw or become poisoned for 1 minute. If the effect ends for the creature or the creature passes its Constitution saving throw, it is immune to the effect for 24 hours. The substance must be washed away with water or 12 hours must past for it to be removed. A successful DC 16 Intelligence (Nature) check reveals the method of removal.

Noticing the trap requires a successful DC 17 Intelligence (Investigation) check. It can be disarmed by removing the vial.

9. Khrull’s Room

You enter a small unpleasant chamber and spot a plain wooden bunk against the far wall. The noise from the engine room must make sleeping very difficult, and you see what appears to be small shrine next to the bed. A cupboard, chest high to a human, is set into the curved wall ahead of you. The room appears empty.

This small, noisy chamber is where Khrull sleeps. Xentarich has given him a particularly uncomfortable posting out of spite. The small shrine is to Khrull’s god, Erythnul, and the cabinet contains Khrull’s spare clothes.


Hiding in the bottom of the cabinet is Khrull’s pet, a giant wolf spider; if the door is opened it leaps out and attacks, probably with surprise, trying to bite the first person it sees.


A successful DC 15 Intelligence (Investigation) check reveals a casket hidden under the bed. The casket contains 40 platinum pieces and a golden holy symbol of Erythnul (100 gp). The casket also contains Khrull’s journal (written in Orc), nothing how displeased he is with the insufficient carnage Xentarich is causing.

10. Treasure Chamber

This small, square chamber of black iron is completely empty save for a heavy iron chest with brass bands against the far wall. A glowing ball of energy hovers in the middle of the room, illuminating the area.

This is Xentarich’s secret treasure chamber. Only he and Torax know of this room.


The center of the room is actually a pit, disguised by a permanent major image spell on the floor. A character can detect that it is an illusion and disbelieve it with a successful DC 19 Intelligence (Investigation) check. Anyone stepping on the illusion falls into area 2 below, hits the trapdoor with enough force to open it, and plummets out of the Colossus to the ground below–a 90-foot fall in all.


The energy ball is actually an advanced will-o’-wisp (see the appendix) placed here as a guardian. The door is airtight to prevent the creature from escaping, and the illusory floor (see below) has been further enhanced to prevent the creature from passing through.

Tactics. The wisp hovers over the trap and playfully dances around the room if the PCs don’t seem inclined to enter the room, attempting to lure a character onto the illusion before attacking. It attacks immediately if the PCs detect the illusory nature of the floor. Attacking the wisp from range automatically breaks the bonds holding it in the chamber, allowing it to attack outside this room. If flees if reduced to 10 hp or less.


Inside the chest is a large sack containing 10,000 sp, 4,500 gp, a silver chalice (200 gp), 3 gems (100 gp each), a potion of love, a potion of speak with animals, and two arcane scrolls of fabricate.

11. Common Room

Before you is a large chamber containing small groups of tables and chairs. A number of abandoned meals lie scattered around the room. You spot a ladder braced against the wall leading to the level above, and a narrow set of steps leading below. Three doors allow access to the rest of this level. A target board on the southern wall has two daggers embedded in it. You can hear a low thunderous rumbling from the north wall.

This area is empty until after the attack. One of the daggers is of masterwork quality (20 gp), offering a +1 bonus to attack rolls made with it. The steps lead to area 4 below, and the ladder leads up to area 14.

12. Barracks

The darkened chamber is unlit but you can still make out a group of uncomfortable looking beds scattered through the room. Even here the sound of the engine can still be heard and must make sleeping difficult. At the foot of each bed is a small wooden casket.

Each small casket contains basic possessions and the spare clothes of each mercenary. The engineers sleep in area 5 now, out of fear of the Storm Hammers.


Unless the alarm is raised, Pwenkin and Yurit, two unarmed Darkblades (see the appendix) sleep here.

Tactics. The two Darkblades leap to their feet and grab their weapons if surprised in their beds. If they heard the PCs approach or the Colossus is on alarm, they’re dressed and ready for battle. Both fight until slain.

To be continued in ‘Heart of the Iron God‘ Part 2: Colossus Chambers 13 – 24

‘Heart of the Iron God’ Index

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