Return to Undermountain
Room 17: The Ice Prison (EL 14)
By Matthew Sernett

Room Summary

Creatures: (13) Five helmed horrors and eight prisoner monsters.
Traps: (Several) There are two traps near the entrance and every cell door is a trap.
Terrain: Ice covers the floor and a severe chill permeates the central room of the ice prison. The ice requires 2 squares of movement, and the DC of Balance and Tumble checks is increased by 5. The severe cold of the room shouldn't be a factor unless a PC remains unprotected in the room for an hour. See page 9 of Frostburn should this happen.
Lighting Conditions: Shadowy illumination until the helmed horrors come out of the ice pillar, then bright illumination.
Magic: Moderate evocation (mindfrost trap) and overwhelming transmutation (the whole room).
Detectable Alignments: Many evil creatures of various type and HD are in the cells. The helmed horrors do not have a detectable alignment.
Secrets: (Several) Two traps are near the entrance and every cell door is a trap.
Treasure: (13,000 gp) The ice pillar holds the wealth of dead prisoners.

Relevant Skill Checks

Balance DC 10: A PC must make a Balance check to charge or run.

Climb DC 25: A PC can climb the walls of the ice prison with this result.

Disable Device DC (varies): See each trap for its Disable Device DC.

Search DC (varies): A PC with trapfinding can discover the traps. See each trap for its Search DC.

The Map

The map for this room is available in two different sizes: One serves as a reference for the DM, and the other is a map with a grid that works nicely with your miniatures.

Each map is presented as a compressed (zipped) Adobe Portable Document Format file (pdf). You need to have Adobe Reader installed to use it. Adobe Reader can be downloaded for free from the Adobe website.

Room Location on the Poster Map: This room is on pieces 4 and 7 of the poster map. You can see the pieces in thumbnail size in the introduction to this series. For a better idea of where this room is, please view the Article Reference Map.

This chamber is a three-story ice prison. Halaster uses it to contain his "criminals" -- monstrous denizens of the dungeon that have tried to escape to the surface too many times. Many of the cells currently hold creatures. Halaster keeps the interior of the cells magically warm, and no creature contained within requires food or water while so confined. Of course, the prison walls are merely made of ice, and prisoners can break through them to escape, but Halaster takes care to imprison only those creatures that his helmed horrors can defeat. Having witnessed other creatures' escape attempts, the current prisoners simply languish or pace about in their cells, waiting for the day when Halaster's whim at last allows them to leave. Halaster keeps most of these criminals here for a few weeks before releasing them back to the dungeon. Most are happy to escape and accept the more expansive prison of Undermountain as their homes. Others persist in trying to leave Halaster's realm, and these Halaster toys with, imprisoning them again or letting them get close to a way out before snatching them back and placing them deeper in the dungeons than before.

It amuses Halaster to allow others to enter the ice prison of their free will. He has instructed his helmed horrors to deal with them as they would escaped prisoners. Should things go awry and prisoners escape due to this open-door policy, it hardly bothers the Mad Mage. Escapees merely flee into Undermountain where he can watch and enjoy their foibles.

The PCs can enter the ice prison through a single passage shut off from the rest of the dungeon by two sets of double doors. When the PCs approach the first set of double doors, read or paraphrase the following text.

A chilly moistness emanates outward from this huge set of stone double doors. The two of them span the hall, each being nearly 5 feet wide and 10 feet tall. The doors bear no ornament or decoration beyond utilitarian handles and a few words in Common, "Enter not ye who would live to leave."

These doors aren't locked or trapped and bear no magic. They stand as mute warning to those who would proceed farther. If the PCs open the doors, read the following text.

Beyond the doors are another set of double doors, and the cold trapped between the doors increases dramatically. Unlike the previous portal, this second set of double doors bears elaborate carvings of what could be stalactites but must be icicles considering the motifs of snow piles and snowflakes. Several long and thick stone icicles droop all the way down the door, resembling bars on a cage. A snowflake in the center of one door bears a dark keyhole.

These doors are trapped to further deter the foolish. Halaster doesn't mind an occasional amusing intrusion into his prison, but he doesn't want the constant invasions of creatures wandering the dungeon. The trap also serves to deter creatures that can't read the warning on the first door.

Double Doors: 4 in. thick; hardness 8; hp 60; break DC 28; Open Lock DC 30 (lock* [good]: hardness 15; hp 30).

*Note that locks built into dungeon doors cannot be attacked separately from the door.

Mindfrost Trap: CR 4; magic device; touch trigger (whenever a creature touches the door); automatic reset; spell effect (mindfrost, 7th-level wizard, 5d6 cold and 1d4 Intelligence damage, Fortitude save half damage); Search DC 29; Disable Device DC 29. For a complete description of the mindfrost spell, see Frostburn.

A creature affected by mindfrost feels an intense cold and an excruciating headache, but there is no outward sign of the effect.

When PCs open the doors, read the following text.

Ice covers the floor of the huge, dimly lit chamber, and it forms walls as well as rooms, which line the exterior of this area. In the center stands a huge pillar of ice at least 15 feet thick. Inside it, about 15 feet above the floor, orange lights waver behind thick ice. The warping effect of the ice makes it impossible to tell the light's source, but the lights hover in what could be another chamber in the ice pillar. Some of the rooms are sealed by similar ice formations, though no light shines in these other areas. Instead, the ice-sealed rooms have dark shapes moving behind them.

If the PCs decide to investigate the strange light more closely, read the following to the players.

A dim purple radiance shines through the ice, as well as around and below the orange glow. Both the brighter orange light and the dimmer lavender luminescence set the pillar aglow and sends a dim radiance across the chamber.

The orange brilliance comes from the flaming swords of five helmed horrors standing in the room beyond the wall. The purple radiance is the eerie light that shines within their hollow armored forms. Halaster placed the helmed horrors here to guard his prisoners. The prisoners lurk within their cells; they're the dark shapes moving behind the ice doors.

Ice Pillar: The ice pillar is hollow inside and has an opening 10 feet up from the floor on the side opposite the entrance to the ice prison.

Ice Pillar: 1 ft. thick; hardness 0; hp 72; break DC 30.

Falling Ice Wall Trap: CR 5; mechanical; location trigger; repair reset; DC 20 Reflex save avoids if the PC is free to move to an adjacent square not affected by the trap; falling ice wall pins those beneath it (8d6, crush); multiple targets (pins all characters in the designated squares); Search DC 20; Disable Device DC 24.

When a creature enters the ice prison and moves out of the designated squares, this trap activates and seals the entrance. Any creatures still in the designated area are damaged and pinned. A DC 20 Escape Artist check allows a PC to slip out from under the wall. The ice wall is 5 feet thick and weighs 2,000 pounds. (This weight is spread out across the wall.) The PCs can work together to lift the ice wall. Each contributes double his maximum load in lifting power (pinned PCs can't contribute). If this is enough to exceed half the wall's weight, they can shift it enough to reduce the Escape Artist DC to 15 for pinned creatures. If the PCs can equal or exceed the wall's weight, they can lift it a few feet off the floor to free pinned creatures. The ice wall can't be moved away from the door due to the construction of the trap.

Ice Wall: 5 ft. thick; hardness 0; hp 180; break DC 30; Escape Artist DC 20 or 15 (see above).

Cell Door Trap: CR 2; mechanical; location trigger; manual reset; Atk +10 melee (3d6, bludgeoning); Search DC 24; Disable Device DC 29.

When a creature enters a cell, its ice door, which weighs 600 pounds, falls. Damage applies only to those underneath the cell door as it falls. Since the cell door is placed on a vertice rather than in a square, it is likely that only a Large or larger creature can be struck by it. A creature struck by the cell door is considered pinned beneath it until the portcullis is lifted.

Cell Door: 1 ft. thick; hardness 0; hp 72; break DC 30.

Cells: Each cell has a 20-foot-high ceiling.Halaster's powerful magic makes the prison cells habitable for any creature. Creatures within a cell with a closed and intact cell door need not breathe, eat, or drink while they remain in the cell. Upon leaving it, they are only as hungry as they were when placed inside. The temperature in the cell is about 50 degrees despite the surrounding ice. For the purposes of dispelling, these effects have a caster level of 30.

A closed cell makes for a great place for the PCs to rest while in Undermountain. Of course, if the PCs destroy Halaster's helmed horror guards, it isn't long before he replaces them with something worse . . .

Helmed Horrors (5): Use the statistics for the Helmed Horror (37/60) from the Underdark miniatures set or the statistics presented on page 175 of Lost Empires of Faerūn. The helmed horrors all wield flaming weapons due to their weapon power ability.

When the ice wall trap triggers or when the PCs otherwise make themselves apparent, the helmed horrors air walk out of the side of their icicle guard room and attack. They attack from one side, hoping to herd one or more PCs into one of the open cells. They never set foot on the ground, always air walking at least a few inches above it so they are never in danger of slipping on the ice.

The helmed horrors strike for lethal damage, a tactic meant to convince a fleeing prisoner that going back into a cell is preferable to death. If a PC is near a cell doorway, a helmed horror might attempt to bull rush the PC inside.

Prisoners: The monsters imprisoned in the cells begin to attack or break the doors to their cells as soon as the PCs start fighting with the helmed horrors. The prisoners see the PCs' intrusion as their best opportunity to escape. Of course, once they escape their cells, the monsters are still locked in the prison with the PCs due to the ice wall trap. Negotiations with some of the prisoners are possible if the PCs didn't attack them during the fight with the helmed horrors, but the prisoners aren't very trusting of the PCs or each other. Place the prisoners in any of the closed cells, one per cell.

Half-Fiend Ogre (1): Use the statistics for the Half-Fiend Ogre (50/60) from the Underdark miniatures set or use the Monster Manual (see pages 147 and 198) to create a half-fiend ogre.

Gray Render (1): Use the statistics for the Gray Render (48/60) from the Underdark miniatures set or use the statistics in the Monster Manual (see page 138).

Dark Naga (1): Use the statistics for the Dark Naga (33/60) from the Underdark miniatures set or use the statistics in the Monster Manual (see page 191).

Stone Giant (1): Use the statistics for the Stone Giant (08/60) from the Angelfire miniatures set or use the statistics in the Monster Manual (see page 124).

Djinni (1): Use the statistics for the Djinni (17/60) from the Angelfire miniatures set or use the statistics in the Monster Manual (see page 114).

Red Slaad (1): Use the statistics for the Red Slaad (33/60) from the Angelfire miniatures set or use the statistics in the Monster Manual (see page 228).

Chain Devil (1): Use the statistics for the Chain Devil (36/60) from the Angelfire miniatures set or use the statistics in the Monster Manual (see page 53).

Troll (1): Use the statistics for the Troll Slasher (59/60) from the Angelfire miniatures set or use the statistics in the Monster Manual (see page 247).

Treasure: The equipment carried by the monsters is part of the treasure. The rest is 13,000 gp worth of coins and equipment inside the ice pillar. This treasure represents the items and wealth of escaping prisoners killed by the helmed horrors. Roll randomly on Table 3-5 in the Dungeon Master's Guide using the 13th-level treasure entry.

Adventure Hooks and Tie-Ins

  • The cells might hold an NPC the PCs are looking for, or a long-term NPC enemy might reside within one.

  • The PCs might release to freedom a monster that they must later face in the dungeon. This option works best if the monster has a personality and name that the PCs learn. Several of the prisoners would work well.

  • If the PCs decide to rest in a cell, they might encounter Halaster himself. The Mad Mage won't be happy with the destruction they've wrought, and he gleefully transports them to another place in the dungeon.

Check out the Return to Undermountain: An Introduction for more details.

Article Reference Map

About the Author

Once Editor-in-Chief of Dragon magazine and now a game designer at Wizards of the Coast, Matthew Sernett wrote in a Dragon editorial that there's nothing in D&D he likes better than when the adventurers flee through the dungeon, running pell-mell through traps and past monsters because what chases them is worse. When he wrote that, Matthew was thinking about Undermountain.

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