D&D 3E/3.5 Collapsing Bridge Mechanics-- 3.5

[Xiek00]

I am trying to create an encounter in which the players are lured onto a bridge in Sharn, then attacked by Emerald Claw assassins. At some point, I'd like charges (or something like them) to be set off on the bridge, causing a slow, steady collapse. What would be a good way to execute this collapse? Any feedback would be greatly appreciated!

Thanks!

 

[HoboGod]

Contingency + Fireball on a few of the bridge's support beams. The contingency trigger could be anything as simple as the original caster, scrying on the party from miles away, saying "click."

Edit: No wait, contingency is for self spells... hmmm, gimmie a minute to think.

 

[HoboGod]

How about a proximity trigger on a fireball spell trap?

 

[Theo R Cwithin]

Are you looking for in-game suggestions to collapse the bridge, or some suggestions for running an encounter on a collapsing bridge? Or both?

To collapse the bridge, fire spell charge as HoboGod suggests could set a wooden bridge on fire. In that case you're dealing with a fiery battle field, which could be really exciting. If the bridge is stone, then maybe a well-placed rock to mud at the base of the supports; that could give a X% per round that a portion of the bridge will topple and start the whole thing collapsing.

For collapsing parts-- whether because of fire or weakened stone-- you could run it like an "expanding pit trap" grows and slowly "eats away" at the bridge. In round 1, a 10x10 hole opens up. In round two, the ground within 10ft of the original hole opens up (so now it's 20x20). Round 3 it expands to 30x30, and so on. Each round, anyone on the collapsing part makes a reflex save to leap to a stable part of the bridge, or else ends up in the river below.

If you have a little more info, I'm sure others will have some ideas. In any event, sounds like a fun encounter!

 

[Xiek00]

First of all, very good ideas, and once again, I am very thankful Originally I was looking for advice on how the bridge should collapse, but I would gladly welcome advice on the encounter itself as well!

As for the request for more detail, the bridge is stone, measuring fifteen feet wide and sixty feet long, with five foot wide barriers on either side. It links two "towers" in the city of Sharn. It is a vaulted bridge that is approximately 75 yards above the ground.

The encounter itself: the trap should spring as the PCs approach a false contact near the middle of the bridge. The ambush would consist of several generic warriors and a combat oriented leader (rather than a wizard or rogue-- the "leaders" of the other two big encounters are an illusionist and a Psion).

 

[Gilladian]

For a stone bridge like you're speaking of, I'd definitely use rock to mud rather than a fireball. As a 5th level spell, it's a bit powerful (18 cubes 10x10x10 of rock turned instantly to mud would be roughly the whole bridge, assuming it is 10' thick) but you could instead say they had some sort of lesser rock to mud salve.

Or stoneshape is only a L3 cleric/druid spell - it affects a 10'cube +1 cube per level, so only 3 cubes at low level. That's enough to push one end of the bridge out of position, and cause it to start collapsing.