Rising and Falling Blocks
Level 11 Elite Blaster
XP 1200

Massive stone blocks rise and fall in shafts near the center of the room.

Trap: Depending on its position, each area can be a barrier or a pit, and creatures can also be squashed under several tons of stone.Perception     DC 28: Slight vibrations in the walls (actually the blocks) suggest that they might be poised to move.Arcana     DC 33: The air is full of tremendous magical residue—kinetic energy of some sort.Initiative +4 (roll A, B, and C separately)TriggerThe trap is triggered by any movement into the room.AttackStandard Action      Area All creatures within area A, B, or C (resolved separately)
Target: Each creature in the areaEffect: On the trap’s initiative count, blocks A and C move in the following pattern:
1. up into the ceiling (bottom of the block flush with the ceiling, top flat against the roof of the opening);
2. down to form walls (bottom and top flush with the floor and ceiling);
3. down into the floor (top flush with the floor);
4. down to the bottom of the 90-foot pit (top 60 feet below the floor);
5. up to floor level (top flush with the floor);
6. and so on in an endless cycle.
Block B moves in the same pattern, but it begins with step 3. Creatures on the edge of a block can make a saving throw when the block moves. If they succeed, they can slide to any unoccupied square beyond the block area and fall prone there. Creatures not on the periphery and creatures who fail their saving throws are at the mercy of the blocks.
Fall into a pit when the block is up: 9d10 falling damage
Fall into a pit when the block is all the way down: 6d10 falling damage
Crushed against ceiling: 2d10 + 40 damage.
Crushed against floor: 3d10 + 50 damage.
Countermeasures     Thievery DC 28: A character in one of the block areas or adjacent to it when the block is fully in the chamber (at step 2) can jam it, thereby preventing further movement.
     Arcana DC 33: Certain carved runes on the blocks can be defaced, which will send the blocks hurtling into the pits one last time.

Published in Dungeon Magazine 175, page(s) 27.