A 10′x10′ trigger plate is located about 40 feet down-slope from the junction; if anyone steps on it, a door slams shut over the original corridor, trapping whoever’s in there on the slope. A moment later, a huge cylindrical boulder drops at the top of the slope and begins accelerating towards the PCs. The boulder is 10-feet wide and 10 feet in diameter, filling the tunnel from side to side and leaving only a few feet between it and the ceiling.

At the end of the tunnel, where lights can be seen, a gelatinous cube waits, filling the doorway. Due to the refraction of the lights streaming in from behind it, the gelatinous cube is easier to spot than normal (DC 20 perception check instead of DC 25). A counter-weighted trap door at the end of the hallway collects the boulder in a storage area beneath the hallway, preventing the boulder from splattering the gelatinous ooze.

Level 5 Obstable, 200 xp (doesn’t include experience for gelatinous cube)

Trap: A boulder runs the PCs down, damaging them and herding them into a waiting gelatinous cube.
Perception:

• DC 12: The character notices the hole from which the boulder drops at the top of the slope.
• DC 22: The character notices the trigger plate.
• DC 17: The character notices the trap door the boulder falls into at the end.
• DC 25: The character notices the gelatinous cube at the end of the hall. Characters within 6 squares of the cube get a +5 circumstance bonus to this check due to the refraction of the light passing through the cube’s body from behind.

Initiative: +7
Speed: 4
Trigger: A character steps on the trigger plate.

Attack
Free action, whenever the boulder moves into a creature.
+10 vs. Reflex
Hit: 2d8+4 damage, and the target is knocked prone. Additionally, the target is pushed along with the boulder, ending in front of it down-slope.
Miss: As hit, but half damage and the target is not knocked prone.

Countermeasures

• A character can jam the trigger plate, allowing safe passage. DC 17 Thievery. Complexity 1 skill challenge (4 successes before 3 failures). Success prevents the door from jamming shut or the boulder from dropping, though the gelatinous cube is still at the end of the tunnel. Failure triggers the trap.
• A character can try to hold the boulder back. Stopping it after it’s started rolling required a DC 22 athletics check. Keeping it stationary after it’s already stopped requires a DC 17 athletics check.
• Characters may force the trap door at the end of the hallway open with a DC 17 athletics check. Inside there is ample room to hide and dodge the boulder when it falls.
• Characters may defeat the gelatinous goo or otherwise bypass it.

When the PCs are about halfway through the hallway, a kobold on the far end activates the trap. Buzzsaws begin emerging from the seams long the wall, cutting at the characters. At the same time, more kobolds spring from hiding at both ends of the hallway and charge them. The blades are set just high enough so that they go over the heads of the kobolds.

Aside from making it difficult to remain silent, the spores of the sentry mushroom do not have any further effect. The hiccups tend to go away a few minutes after exposure to the mushrooms’ spores ends.

The same thing happens if anyone else enters the room. They all turn invisible, including anything they’re carrying. If anything is tossed into the room, it, too, turns invisible.

The room is used to store treasure, and there are a couple of invisible treasure chests hidden inside. Additionally, there is a magical beast lurking in the room, one for whom lack of sight is not a hindrance.

Shortly after they enter the room, the door they entered through slams shut. The floor in front of that door drops, revealing spinning, spike-covered drums designed to pulverize anything that falls into them.

At the same time, the floor begins moving like an escalator towards the deadly pit. And as if that wasn’t bad enough, a magical device begins summoning zombies non-stop at the far end of the room.

It is up to the characters to make it to the other end of the room, swimming upstream through the living dead. Can they make it out alive, or will they be bogged down and killed?

As soon as one of the characters gets about half way into the room, the doors slam shut. A buzzing sound can be heard, and the hairs on the backs of the characters’ necks begins to stand on end.

A moment later, a golem drops into one of the alcoves and begins attacking the PCs. As soon as it begins, the chrome spheres on the ceiling start shooting bolts of electricity at anything under them. Every round, anyone underneath a sphere gets zapped, harming the PCs and healing the golem.

The spheres themselves are extremely fragile, and any damage at all will shatter them. They’re also very small, though, and so are somewhat difficult targets.

If a character climbs up one of the holes in the alcoves, he’ll find above the ceiling a massive power generator. If destroyed or disabled, the spheres will lose their charges.

If you want to increase the lethality, you can thrown in some more electrically-based monsters. For example, Shock Skeletons, which are skeletons plated with various metals; essentially, walking batteries. They can drop from the alcoves in random intervals, and unleash electrical blasts at the PCs or at the golem.