Magic Force Bridge
Trap
Level 19 Blaster
XP 2400

Bridges of golden magic force blink on and off, connecting and disconnecting the floating platforms to and from one another.

Trap: When the beholder reveals itself, the bridges start to cycle through their off-active-push-active cycle.Perception     DC 28: There seems to be a pattern to the timing: three rounds on, one round off.     DC 33: There are faint clouds of dust that move on each bridge in the second round of the bridge being on, as if there’s a wind there.Arcana     DC 33: There’s a surge in kinetic energy at each bridge during the second round.Initiative +8TriggerOnce activated with a minor action from the beholder, roll 1d4 to determine which bridges will shut down first (1 = 1 and 5, 2 = 2 and 6, 3 = 3 and 7, 4 = 4 and 8). Then roll initiative for the bridges, and in the following round those bridges shut down. Each subsequent round at that initiative point, two more bridges close down (the next two numerically), and the bridges that were inactive become active again. Add two more bridges to the pattern until all have activated once (in the fourth round), then continue cycling through in order in the off-active-push-active cycle. For example, if the initial 1d4 throw is 3, then in the first round, bridges 3 and 7 shut off. In the second round, bridges 4 and 8 shut off and bridges 3 and 7 reactivate. In the third round, bridges 1 and 5 shut off, bridges 4 and 8 reactivate, and bridges 3 and 7 make their push attack. In the fourth round, bridges 2 and 6 shut off, bridges 1 and 5 turn back on, bridges 4 and 8 make a push attack, and bridges 3 and 7 remain active. In the fifth round, bridges 3 and 7 shut off, bridges 4 and 8 remain active, bridges 1 and 5 make a push attack, and bridges 2 and 6 turn back on again. This cycle repeats until the beholder is slain.Attack (during a "push" round for that bridge)Attack: +22 vs. FortitudeHit: 3d12 + 5 damage and push 3 squares and knock prone.Effect: Target is pushed one square away from the center of the bridge and must make a saving throw to be prone and clinging to the edge; targets that fail take 12d10 damage.Effect (during an "off" round for that bridge): Characters standing on the bridge when it deactivates fall, taking 12d10 damage when they hit the cavern floor. Creatures who are adjacent to a floating platform can attempt a saving throw; if they succeed, they can instead be prone in an unoccupied, adjacent platform square.Countermeasures     Arcana DC 33: An adjacent character can disable the trap with a successful check. The bridge no longer deactivates to cause characters to fall through and the whirlwind push effect ceases for the duration of the encounter.

Published in Dungeon Magazine 175, page(s) 39.