Ice Fall

Complex trap (level 5–10, deadly threat)

At the heart of a temple devoted to a winter deity lies a hard-to-access shrine. After passing over a bridge of ice that crosses a ravine so deep that the bottom cannot be seen, explorers come to a set of massive double doors cast with the deity’s likeness. Inside is a 40-foot-wide and 80-foot-deep room with an intricately carved altar made of ice at the far end. There appears to be writing amongst the carvings. The ceiling is covered in massive icicles except for a 20-foot-square area in front of the altar. The walls, floor, and ceiling are covered with a layer of cloudy ice and a faint breeze swirls within the room.

Trigger. The area with no icicles above it is actually a thin coating of opaque ice over a 40-foot-deep pit. Whenever a weight of 5 pounds or more is placed on the ice, it collapses. A creature in the area must succeed on a DC 20 Dexterity saving throw or fall in, taking 14 (4d6) bludgeoning damage. If anything, including the broken ice, hits the bottom of the put, then the rest of the trap activates.

Initiative. The trap acts on initiative count 20 and initiative count 10.

Active Elements. Massive icicles fall from the ceiling everywhere except in the pit, threatening to spear those inside the rest of the room. A blast of cold emanates in a 15-foot-radius hemisphere from the double doors:

• Arboreal Doors (Initiative 20)—On the round the trap activates, the doors slam shut and lock while a sheet of ice forms over them. Every round after the first, a blast of freezing wind gusts from the doors, affecting an area 15 feet from the door. Any creature in the area must attempt a DC 20 Strength saving throw or suffer 11 (2d10) cold damage and be pushed 15 feet from the door. Those that successfully save take half damage and are not pushed.
• Falling Icicles (Initiative 10)—Massive icicles fall from the ceiling, attacking every creature in the room, not in the pit, with a +8 bonus to the ranged attack roll and dealing 22 (4d10) piercing damage on a hit.
• Self-Sealing, Water-Filled Pit (Initiative 10)—On the second round, freezing water begins to pour into the pit from small pipes embedded in the walls, raising the water level by 5 feet. On the third round, a stone door begins to slide out from the wall of the pit, completely sealing it off at the beginning of round six.

Constant Elements. Vicious winds from an unseen source swirl around the room, further propelling the shards of ice from the broken icicles into deadly shrapnel. Freezing water threatens to sap the strength of those in the pit:

• Freezing Water—Any creature that starts it turn in the freezing water of the pit takes 11 (2d10) cold damage. A successful DC 20 Constitution saving throw halves the damage.
• Icy Shrapnel—At the start of each creatures’ turn, they must make a DC 20 Dexterity saving throw. Those that fail take 5 (1d10) piercing damage from the flying shards of ice.
• Vicious Winds—The winds impose disadvantage on Wisdom (Perception) checks that rely on hearing, and they also extinguish open flames, disperse fog, and make flying by nonmagical means nearly impossible. A flying creature in a strong wind must land at the end of its turn or fall. The wind, combined with the icy floor, make the ground difficult terrain.

Dynamic Elements. As more icicles fall, more shrapnel builds up:

• More Shrapnel—Each round, more icicles fall and shatter, resulting in more shrapnel. Increase the Icy Shrapnel damage by 5 (1d10) piercing damage for each round after the first until the characters escape or 10 rounds have passed.

Countermeasures. Each part of the trap has its own countermeasures:

• Altar—The altar is carved with an intricate incantation in Primordial that exalts the god of winter. A character can successfully decipher the coded incantation with a DC 15 Intelligence (Investigation) check. A character that loudly recites the incantation with either a successful DC 15 Intelligence (Arcana) or Wisdom (Religion) check causes the vicious winds, icy shrapnel, falling icicles, and self-sealing door of the pit to all stop. A character gets advantage on both of these checks if they understand Primordial.
• Arboreal Doors—The ice covering the doors has AC 12 and 15 hp, and it is vulnerable to fire damage. Once the ice is shattered, the doors can be unlocked by succeeding on a DC 15 Dexterity (thieves’ tools) check or battering it down with a successful DC 20 Strength check. There are obvious glowing runes carved on the door that cause the blast of freezing winds. These runes can be disabled with a successful DC 20 Arcana check or by doing 15 points of damage to the doors. The doors have an AC of 15 and 50 hp but are immune to poison and psychic damage.
• Falling Icicles—Anything that blocks the line of effect to the ceiling, such as a magical wall, protects against the falling icicles. The icicles can be preemptively destroyed by doing 10 points of fire damage per 10-foot square of the ceiling. Doing so creates an area devoid of falling icicles.
• Self-Sealing, Water-Filled Pit—Climbing out of the icy pit requires a DC 20 Strength (Athletics) check. Characters that fail by 5 or more slip and take falling damage. (Decrease the distance fallen by the amount of water in the pit.) The self-sealing door can be disabled with a successful DC 20 Dexterity (thieves’ tools) or can be jammed with a successful DC 20 Strength check each round. The door has an AC of 12 and 30 hp but is immune to poison and psychic damage.
• Vicious Winds and Icy Shrapnel—Anything that surrounds a character, such as a magical wall, can be used to protect them from the icy shrapnel. In addition, a character with a shield can move into a corner and take the Dodge action to avoid shrapnel damage for that round. The winds and shrapnel cease when the doors are opened.

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